diff --git a/taglib/ape/apefile.cpp b/taglib/ape/apefile.cpp
index cb652242..24158cf3 100644
--- a/taglib/ape/apefile.cpp
+++ b/taglib/ape/apefile.cpp
@@ -66,10 +66,10 @@ public:
     delete properties;
   }
 
-  long APELocation;
+  offset_t APELocation;
   uint APESize;
 
-  long ID3v1Location;
+  offset_t ID3v1Location;
 
   TagUnion tag;
 
@@ -272,7 +272,7 @@ void APE::File::read(bool readProperties, Properties::ReadStyle /* propertiesSty
   }
 }
 
-long APE::File::findAPE()
+offset_t APE::File::findAPE()
 {
   if(!isValid())
     return -1;
@@ -282,7 +282,7 @@ long APE::File::findAPE()
   else
     seek(-32, End);
 
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(8) == APE::Tag::fileIdentifier())
     return p;
@@ -290,13 +290,13 @@ long APE::File::findAPE()
   return -1;
 }
 
-long APE::File::findID3v1()
+offset_t APE::File::findID3v1()
 {
   if(!isValid())
     return -1;
 
   seek(-128, End);
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(3) == ID3v1::Tag::fileIdentifier())
     return p;
diff --git a/taglib/ape/apefile.h b/taglib/ape/apefile.h
index 8b187f6a..ec55207f 100644
--- a/taglib/ape/apefile.h
+++ b/taglib/ape/apefile.h
@@ -189,8 +189,8 @@ namespace TagLib {
 
       void read(bool readProperties, Properties::ReadStyle propertiesStyle);
       void scan();
-      long findID3v1();
-      long findAPE();
+      offset_t findID3v1();
+      offset_t findAPE();
 
       class FilePrivate;
       FilePrivate *d;
diff --git a/taglib/ape/apeproperties.cpp b/taglib/ape/apeproperties.cpp
index b4fcec6a..c99996f0 100644
--- a/taglib/ape/apeproperties.cpp
+++ b/taglib/ape/apeproperties.cpp
@@ -39,7 +39,7 @@ using namespace TagLib;
 class APE::Properties::PropertiesPrivate
 {
 public:
-  PropertiesPrivate(File *file, long streamLength) :
+  PropertiesPrivate(File *file, offset_t streamLength) :
     length(0),
     bitrate(0),
     sampleRate(0),
@@ -58,7 +58,7 @@ public:
   int bitsPerSample;
   uint sampleFrames;
   File *file;
-  long streamLength;
+  offset_t streamLength;
 };
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -119,7 +119,7 @@ TagLib::uint APE::Properties::sampleFrames() const
 void APE::Properties::read()
 {
   // First we are searching the descriptor
-  long offset = findDescriptor();
+  offset_t offset = findDescriptor();
   if(offset < 0)
     return;
 
@@ -138,9 +138,9 @@ void APE::Properties::read()
   }
 }
 
-long APE::Properties::findDescriptor()
+offset_t APE::Properties::findDescriptor()
 {
-  long ID3v2Location = findID3v2();
+  offset_t ID3v2Location = findID3v2();
   long ID3v2OriginalSize = 0;
   bool hasID3v2 = false;
   if(ID3v2Location >= 0) {
@@ -150,7 +150,7 @@ long APE::Properties::findDescriptor()
       hasID3v2 = true;
   }
 
-  long offset = 0;
+  offset_t offset = 0;
   if(hasID3v2)
     offset = d->file->find("MAC ", ID3v2Location + ID3v2OriginalSize);
   else
@@ -164,7 +164,7 @@ long APE::Properties::findDescriptor()
   return offset;
 }
 
-long APE::Properties::findID3v2()
+offset_t APE::Properties::findID3v2()
 {
   if(!d->file->isValid())
     return -1;
@@ -201,7 +201,7 @@ void APE::Properties::analyzeCurrent()
   uint finalFrameBlocks = header.mid(8, 4).toUInt(false);
   d->sampleFrames = totalFrames > 0 ? (totalFrames -  1) * blocksPerFrame + finalFrameBlocks : 0;
   d->length = d->sampleRate > 0 ? d->sampleFrames / d->sampleRate : 0;
-  d->bitrate = d->length > 0 ? ((d->streamLength * 8L) / d->length) / 1000 : 0;
+  d->bitrate = d->length > 0 ? static_cast<int>(d->streamLength * 8L / d->length / 1000) : 0;
 }
 
 void APE::Properties::analyzeOld()
@@ -226,6 +226,6 @@ void APE::Properties::analyzeOld()
   uint finalFrameBlocks = header.mid(22, 4).toUInt(false);
   uint totalBlocks = totalFrames > 0 ? (totalFrames - 1) * blocksPerFrame + finalFrameBlocks : 0;
   d->length = totalBlocks / d->sampleRate;
-  d->bitrate = d->length > 0 ? ((d->streamLength * 8L) / d->length) / 1000 : 0;
+  d->bitrate = d->length > 0 ? static_cast<int>(d->streamLength * 8L / d->length / 1000) : 0;
 }
 
diff --git a/taglib/ape/apeproperties.h b/taglib/ape/apeproperties.h
index f154ec34..ff439568 100644
--- a/taglib/ape/apeproperties.h
+++ b/taglib/ape/apeproperties.h
@@ -84,8 +84,8 @@ namespace TagLib {
 
       void read();
 
-      long findDescriptor();
-      long findID3v2();
+      offset_t findDescriptor();
+      offset_t findID3v2();
 
       void analyzeCurrent();
       void analyzeOld();
diff --git a/taglib/ape/apetag.cpp b/taglib/ape/apetag.cpp
index 3dcae8c0..31dccc48 100644
--- a/taglib/ape/apetag.cpp
+++ b/taglib/ape/apetag.cpp
@@ -49,7 +49,7 @@ public:
   TagPrivate() : file(0), footerLocation(-1), tagLength(0) {}
 
   TagLib::File *file;
-  long footerLocation;
+  offset_t footerLocation;
   long tagLength;
 
   Footer footer;
@@ -66,7 +66,7 @@ APE::Tag::Tag() : TagLib::Tag()
   d = new TagPrivate;
 }
 
-APE::Tag::Tag(TagLib::File *file, long footerLocation) : TagLib::Tag()
+APE::Tag::Tag(TagLib::File *file, offset_t footerLocation) : TagLib::Tag()
 {
   d = new TagPrivate;
   d->file = file;
diff --git a/taglib/ape/apetag.h b/taglib/ape/apetag.h
index c1f12e29..9b78d5dd 100644
--- a/taglib/ape/apetag.h
+++ b/taglib/ape/apetag.h
@@ -66,7 +66,7 @@ namespace TagLib {
        * Create an APE tag and parse the data in \a file with APE footer at
        * \a tagOffset.
        */
-      Tag(TagLib::File *file, long footerLocation);
+      Tag(TagLib::File *file, offset_t footerLocation);
 
       /*!
        * Destroys this Tag instance.
diff --git a/taglib/asf/asffile.cpp b/taglib/asf/asffile.cpp
index 455631f8..d27fefcb 100644
--- a/taglib/asf/asffile.cpp
+++ b/taglib/asf/asffile.cpp
@@ -158,7 +158,7 @@ ASF::File::HeaderExtensionObject::~HeaderExtensionObject()
 void ASF::File::BaseObject::parse(ASF::File *file, unsigned int size)
 {
   data.clear();
-  if (size > 24 && size <= (unsigned int)(file->length()))
+  if (size > 24 && static_cast<offset_t>(size) <= file->length())
     data = file->readBlock(size - 24);
   else
     data = ByteVector::null;
diff --git a/taglib/flac/flacfile.cpp b/taglib/flac/flacfile.cpp
index c85d9590..d27bb555 100644
--- a/taglib/flac/flacfile.cpp
+++ b/taglib/flac/flacfile.cpp
@@ -78,10 +78,10 @@ public:
   }
 
   const ID3v2::FrameFactory *ID3v2FrameFactory;
-  long ID3v2Location;
+  offset_t ID3v2Location;
   uint ID3v2OriginalSize;
 
-  long ID3v1Location;
+  offset_t ID3v1Location;
 
   TagUnion tag;
 
@@ -90,9 +90,9 @@ public:
   ByteVector xiphCommentData;
   List<MetadataBlock *> blocks;
 
-  long flacStart;
-  long streamStart;
-  long streamLength;
+  offset_t flacStart;
+  offset_t streamStart;
+  offset_t streamLength;
   bool scanned;
 
   bool hasXiphComment;
@@ -237,7 +237,7 @@ bool FLAC::File::save()
 
   // Adjust the padding block(s)
 
-  long originalLength = d->streamStart - d->flacStart;
+  uint originalLength = static_cast<uint>(d->streamStart - d->flacStart);
   int paddingLength = originalLength - data.size() - 4;
   if (paddingLength < 0) {
     paddingLength = MinPaddingLength;
@@ -356,7 +356,7 @@ ByteVector FLAC::File::xiphCommentData() const
   return (isValid() && d->hasXiphComment) ? d->xiphCommentData : ByteVector();
 }
 
-long FLAC::File::streamLength()
+offset_t FLAC::File::streamLength()
 {
   return d->streamLength;
 }
@@ -371,7 +371,7 @@ void FLAC::File::scan()
   if(!isValid())
     return;
 
-  long nextBlockOffset;
+  offset_t nextBlockOffset;
 
   if(d->hasID3v2)
     nextBlockOffset = find("fLaC", d->ID3v2Location + d->ID3v2OriginalSize);
@@ -486,13 +486,13 @@ void FLAC::File::scan()
   d->scanned = true;
 }
 
-long FLAC::File::findID3v1()
+offset_t FLAC::File::findID3v1()
 {
   if(!isValid())
     return -1;
 
   seek(-128, End);
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(3) == ID3v1::Tag::fileIdentifier())
     return p;
@@ -500,7 +500,7 @@ long FLAC::File::findID3v1()
   return -1;
 }
 
-long FLAC::File::findID3v2()
+offset_t FLAC::File::findID3v2()
 {
   if(!isValid())
     return -1;
diff --git a/taglib/flac/flacfile.h b/taglib/flac/flacfile.h
index 716d4478..6bbd85c9 100644
--- a/taglib/flac/flacfile.h
+++ b/taglib/flac/flacfile.h
@@ -215,7 +215,7 @@ namespace TagLib {
        *
        * \deprecated This method will not be public in a future release.
        */
-      long streamLength();  // BIC: remove
+      offset_t streamLength();  // BIC: remove
 
       /*!
        * Returns a list of pictures attached to the FLAC file.
@@ -247,10 +247,10 @@ namespace TagLib {
 
       void read(bool readProperties, Properties::ReadStyle propertiesStyle);
       void scan();
-      long findID3v2();
-      long findID3v1();
+      offset_t findID3v2();
+      offset_t findID3v1();
       ByteVector xiphCommentData() const;
-      long findPaddingBreak(long nextPageOffset, long targetOffset, bool *isLast);
+      offset_t findPaddingBreak(long nextPageOffset, long targetOffset, bool *isLast);
 
       class FilePrivate;
       FilePrivate *d;
diff --git a/taglib/flac/flacproperties.cpp b/taglib/flac/flacproperties.cpp
index 8bdc5d8d..57de55f4 100644
--- a/taglib/flac/flacproperties.cpp
+++ b/taglib/flac/flacproperties.cpp
@@ -34,7 +34,7 @@ using namespace TagLib;
 class FLAC::Properties::PropertiesPrivate
 {
 public:
-  PropertiesPrivate(ByteVector d, long st, ReadStyle s) :
+  PropertiesPrivate(ByteVector d, offset_t st, ReadStyle s) :
     data(d),
     streamLength(st),
     style(s),
@@ -46,7 +46,7 @@ public:
     sampleFrames(0) {}
 
   ByteVector data;
-  long streamLength;
+  offset_t streamLength;
   ReadStyle style;
   int length;
   int bitrate;
@@ -61,7 +61,7 @@ public:
 // public members
 ////////////////////////////////////////////////////////////////////////////////
 
-FLAC::Properties::Properties(ByteVector data, long streamLength, ReadStyle style) : AudioProperties(style)
+FLAC::Properties::Properties(ByteVector data, offset_t streamLength, ReadStyle style) : AudioProperties(style)
 {
   d = new PropertiesPrivate(data, streamLength, style);
   read();
@@ -155,7 +155,7 @@ void FLAC::Properties::read()
   d->sampleFrames = (hi << 32) | lo;
 
   if(d->sampleRate > 0)
-    d->length = int(d->sampleFrames / d->sampleRate);
+    d->length = static_cast<int>(d->sampleFrames / d->sampleRate);
 
   // Uncompressed bitrate:
 
@@ -163,7 +163,7 @@ void FLAC::Properties::read()
 
   // Real bitrate:
 
-  d->bitrate = d->length > 0 ? ((d->streamLength * 8UL) / d->length) / 1000 : 0;
+  d->bitrate = d->length > 0 ? static_cast<int>(d->streamLength * 8L / d->length / 1000) : 0;
 
   d->signature = d->data.mid(pos, 32);
 }
diff --git a/taglib/flac/flacproperties.h b/taglib/flac/flacproperties.h
index c1458981..8b59b4d9 100644
--- a/taglib/flac/flacproperties.h
+++ b/taglib/flac/flacproperties.h
@@ -50,7 +50,7 @@ namespace TagLib {
        * ByteVector \a data.
        */
        // BIC: switch to const reference
-      Properties(ByteVector data, long streamLength, ReadStyle style = Average);
+      Properties(ByteVector data, offset_t streamLength, ReadStyle style = Average);
 
       /*!
        * Create an instance of FLAC::Properties with the data read from the
diff --git a/taglib/it/itfile.cpp b/taglib/it/itfile.cpp
index 4e049518..30638c97 100644
--- a/taglib/it/itfile.cpp
+++ b/taglib/it/itfile.cpp
@@ -155,7 +155,7 @@ bool IT::File::save()
   if(!readU16L(special))
     return false;
 
-  ulong fileSize = File::length();
+  ulong fileSize = static_cast<ulong>(File::length());
   if(special & Properties::MessageAttached) {
     seek(54);
     if(!readU16L(messageLength) || !readU32L(messageOffset))
diff --git a/taglib/mp4/mp4atom.cpp b/taglib/mp4/mp4atom.cpp
index 1681ec80..92e0c17f 100644
--- a/taglib/mp4/mp4atom.cpp
+++ b/taglib/mp4/mp4atom.cpp
@@ -152,7 +152,7 @@ MP4::Atom::path(MP4::AtomList &path, const char *name1, const char *name2, const
 MP4::Atoms::Atoms(File *file)
 {
   file->seek(0, File::End);
-  long end = file->tell();
+  offset_t end = file->tell();
   file->seek(0);
   while(file->tell() + 8 <= end) {
     MP4::Atom *atom = new MP4::Atom(file);
diff --git a/taglib/mp4/mp4atom.h b/taglib/mp4/mp4atom.h
index ea5091a8..9a01f87d 100644
--- a/taglib/mp4/mp4atom.h
+++ b/taglib/mp4/mp4atom.h
@@ -82,7 +82,7 @@ namespace TagLib {
         Atom *find(const char *name1, const char *name2 = 0, const char *name3 = 0, const char *name4 = 0);
         bool path(AtomList &path, const char *name1, const char *name2 = 0, const char *name3 = 0);
         AtomList findall(const char *name, bool recursive = false);
-        long offset;
+        offset_t offset;
         long length;
         TagLib::ByteVector name;
         AtomList children;
diff --git a/taglib/mp4/mp4tag.cpp b/taglib/mp4/mp4tag.cpp
index f929ef64..162e66e9 100644
--- a/taglib/mp4/mp4tag.cpp
+++ b/taglib/mp4/mp4tag.cpp
@@ -514,7 +514,7 @@ MP4::Tag::updateParents(AtomList &path, long delta, int ignore)
 }
 
 void
-MP4::Tag::updateOffsets(long delta, long offset)
+MP4::Tag::updateOffsets(long delta, offset_t offset)
 {
   MP4::Atom *moov = d->atoms->find("moov");
   if(moov) {
@@ -597,7 +597,7 @@ MP4::Tag::saveNew(ByteVector &data)
     data = renderAtom("udta", data);
   }
 
-  long offset = path[path.size() - 1]->offset + 8;
+  offset_t offset = path[path.size() - 1]->offset + 8;
   d->file->insert(data, offset, 0);
 
   updateParents(path, data.size());
@@ -608,7 +608,7 @@ void
 MP4::Tag::saveExisting(ByteVector &data, AtomList &path)
 {
   MP4::Atom *ilst = path[path.size() - 1];
-  long offset = ilst->offset;
+  offset_t offset = ilst->offset;
   long length = ilst->length;
 
   MP4::Atom *meta = path[path.size() - 2];
diff --git a/taglib/mp4/mp4tag.h b/taglib/mp4/mp4tag.h
index b5ea6ebb..bee7298b 100644
--- a/taglib/mp4/mp4tag.h
+++ b/taglib/mp4/mp4tag.h
@@ -96,7 +96,7 @@ namespace TagLib {
         TagLib::ByteVector renderCovr(const ByteVector &name, Item &item);
 
         void updateParents(AtomList &path, long delta, int ignore = 0);
-        void updateOffsets(long delta, long offset);
+        void updateOffsets(long delta, offset_t offset);
 
         void saveNew(TagLib::ByteVector &data);
         void saveExisting(TagLib::ByteVector &data, AtomList &path);
diff --git a/taglib/mpc/mpcfile.cpp b/taglib/mpc/mpcfile.cpp
index 519a0467..5f377155 100644
--- a/taglib/mpc/mpcfile.cpp
+++ b/taglib/mpc/mpcfile.cpp
@@ -64,13 +64,13 @@ public:
     delete properties;
   }
 
-  long APELocation;
+  offset_t APELocation;
   uint APESize;
 
-  long ID3v1Location;
+  offset_t ID3v1Location;
 
   ID3v2::Header *ID3v2Header;
-  long ID3v2Location;
+  offset_t ID3v2Location;
   uint ID3v2Size;
 
   TagUnion tag;
@@ -314,7 +314,7 @@ void MPC::File::read(bool readProperties, Properties::ReadStyle /* propertiesSty
   }
 }
 
-long MPC::File::findAPE()
+offset_t MPC::File::findAPE()
 {
   if(!isValid())
     return -1;
@@ -324,7 +324,7 @@ long MPC::File::findAPE()
   else
     seek(-32, End);
 
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(8) == APE::Tag::fileIdentifier())
     return p;
@@ -332,13 +332,13 @@ long MPC::File::findAPE()
   return -1;
 }
 
-long MPC::File::findID3v1()
+offset_t MPC::File::findID3v1()
 {
   if(!isValid())
     return -1;
 
   seek(-128, End);
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(3) == ID3v1::Tag::fileIdentifier())
     return p;
@@ -346,7 +346,7 @@ long MPC::File::findID3v1()
   return -1;
 }
 
-long MPC::File::findID3v2()
+offset_t MPC::File::findID3v2()
 {
   if(!isValid())
     return -1;
diff --git a/taglib/mpc/mpcfile.h b/taglib/mpc/mpcfile.h
index 167b768e..f3f4ac7d 100644
--- a/taglib/mpc/mpcfile.h
+++ b/taglib/mpc/mpcfile.h
@@ -191,9 +191,9 @@ namespace TagLib {
 
       void read(bool readProperties, Properties::ReadStyle propertiesStyle);
       void scan();
-      long findAPE();
-      long findID3v1();
-      long findID3v2();
+      offset_t findAPE();
+      offset_t findID3v1();
+      offset_t findID3v2();
 
       class FilePrivate;
       FilePrivate *d;
diff --git a/taglib/mpc/mpcproperties.cpp b/taglib/mpc/mpcproperties.cpp
index 23d41987..85af7cf7 100644
--- a/taglib/mpc/mpcproperties.cpp
+++ b/taglib/mpc/mpcproperties.cpp
@@ -36,7 +36,7 @@ using namespace TagLib;
 class MPC::Properties::PropertiesPrivate
 {
 public:
-  PropertiesPrivate(long length, ReadStyle s) :
+  PropertiesPrivate(offset_t length, ReadStyle s) :
     streamLength(length),
     style(s),
     version(0),
@@ -51,7 +51,7 @@ public:
     albumGain(0),
     albumPeak(0) {}
 
-  long streamLength;
+  offset_t streamLength;
   ReadStyle style;
   int version;
   int length;
@@ -71,13 +71,13 @@ public:
 // public members
 ////////////////////////////////////////////////////////////////////////////////
 
-MPC::Properties::Properties(const ByteVector &data, long streamLength, ReadStyle style) : AudioProperties(style)
+MPC::Properties::Properties(const ByteVector &data, offset_t streamLength, ReadStyle style) : AudioProperties(style)
 {
   d = new PropertiesPrivate(streamLength, style);
   readSV7(data);
 }
 
-MPC::Properties::Properties(File *file, long streamLength, ReadStyle style) : AudioProperties(style)
+MPC::Properties::Properties(File *file, offset_t streamLength, ReadStyle style) : AudioProperties(style)
 {
   d = new PropertiesPrivate(streamLength, style);
   ByteVector magic = file->readBlock(4);
@@ -214,7 +214,7 @@ void MPC::Properties::readSV8(File *file)
       d->channels = flags[7] * 8 + flags[6] * 4 + flags[5] * 2 + flags[4] + 1;
 
       if((d->sampleFrames - begSilence) != 0)
-        d->bitrate = (int)(d->streamLength * 8.0 * d->sampleRate / (d->sampleFrames - begSilence));
+        d->bitrate = static_cast<int>(d->streamLength * 8.0 * d->sampleRate / (d->sampleFrames - begSilence));
       d->bitrate = d->bitrate / 1000;
 
       d->length = (d->sampleFrames - begSilence) / d->sampleRate;
@@ -311,6 +311,6 @@ void MPC::Properties::readSV7(const ByteVector &data)
   d->length = d->sampleRate > 0 ? (d->sampleFrames + (d->sampleRate / 2)) / d->sampleRate : 0;
 
   if(!d->bitrate)
-    d->bitrate = d->length > 0 ? ((d->streamLength * 8L) / d->length) / 1000 : 0;
+    d->bitrate = d->length > 0 ? static_cast<int>(d->streamLength * 8L / d->length / 1000) : 0;
 }
 
diff --git a/taglib/mpc/mpcproperties.h b/taglib/mpc/mpcproperties.h
index adf40d83..1a66c64e 100644
--- a/taglib/mpc/mpcproperties.h
+++ b/taglib/mpc/mpcproperties.h
@@ -53,13 +53,13 @@ namespace TagLib {
        *
        * This constructor is deprecated. It only works for MPC version up to 7.
        */
-      Properties(const ByteVector &data, long streamLength, ReadStyle style = Average);
+      Properties(const ByteVector &data, offset_t streamLength, ReadStyle style = Average);
 
       /*!
        * Create an instance of MPC::Properties with the data read directly
        * from a MPC::File.
        */
-      Properties(File *file, long streamLength, ReadStyle style = Average);
+      Properties(File *file, offset_t streamLength, ReadStyle style = Average);
 
       /*!
        * Destroys this MPC::Properties instance.
diff --git a/taglib/mpeg/id3v1/id3v1tag.cpp b/taglib/mpeg/id3v1/id3v1tag.cpp
index ec83077f..891e0d0c 100644
--- a/taglib/mpeg/id3v1/id3v1tag.cpp
+++ b/taglib/mpeg/id3v1/id3v1tag.cpp
@@ -38,7 +38,7 @@ public:
   TagPrivate() : file(0), tagOffset(-1), track(0), genre(255) {}
 
   File *file;
-  long tagOffset;
+  offset_t tagOffset;
 
   String title;
   String artist;
@@ -80,7 +80,7 @@ ID3v1::Tag::Tag() : TagLib::Tag()
   d = new TagPrivate;
 }
 
-ID3v1::Tag::Tag(File *file, long tagOffset) : TagLib::Tag()
+ID3v1::Tag::Tag(File *file, offset_t tagOffset) : TagLib::Tag()
 {
   d = new TagPrivate;
   d->file = file;
diff --git a/taglib/mpeg/id3v1/id3v1tag.h b/taglib/mpeg/id3v1/id3v1tag.h
index 4c0eba2c..27530887 100644
--- a/taglib/mpeg/id3v1/id3v1tag.h
+++ b/taglib/mpeg/id3v1/id3v1tag.h
@@ -111,7 +111,7 @@ namespace TagLib {
        * Create an ID3v1 tag and parse the data in \a file starting at
        * \a tagOffset.
        */
-      Tag(File *file, long tagOffset);
+      Tag(File *file, offset_t tagOffset);
 
       /*!
        * Destroys this Tag instance.
diff --git a/taglib/mpeg/id3v2/id3v2tag.cpp b/taglib/mpeg/id3v2/id3v2tag.cpp
index c26ffef2..d0ef0d67 100644
--- a/taglib/mpeg/id3v2/id3v2tag.cpp
+++ b/taglib/mpeg/id3v2/id3v2tag.cpp
@@ -59,7 +59,7 @@ public:
   }
 
   File *file;
-  long tagOffset;
+  offset_t tagOffset;
   const FrameFactory *factory;
 
   Header header;
@@ -101,7 +101,7 @@ ID3v2::Tag::Tag() : TagLib::Tag()
   d->factory = FrameFactory::instance();
 }
 
-ID3v2::Tag::Tag(File *file, long tagOffset, const FrameFactory *factory) :
+ID3v2::Tag::Tag(File *file, offset_t tagOffset, const FrameFactory *factory) :
   TagLib::Tag()
 {
   d = new TagPrivate;
diff --git a/taglib/mpeg/id3v2/id3v2tag.h b/taglib/mpeg/id3v2/id3v2tag.h
index 946a83f5..43232d43 100644
--- a/taglib/mpeg/id3v2/id3v2tag.h
+++ b/taglib/mpeg/id3v2/id3v2tag.h
@@ -159,7 +159,7 @@ namespace TagLib {
        *
        * \see FrameFactory
        */
-      Tag(File *file, long tagOffset,
+      Tag(File *file, offset_t tagOffset,
           const FrameFactory *factory = FrameFactory::instance());
 
       /*!
diff --git a/taglib/mpeg/mpegfile.cpp b/taglib/mpeg/mpegfile.cpp
index ec094cdc..038c1c8b 100644
--- a/taglib/mpeg/mpegfile.cpp
+++ b/taglib/mpeg/mpegfile.cpp
@@ -70,14 +70,14 @@ public:
 
   const ID3v2::FrameFactory *ID3v2FrameFactory;
 
-  long ID3v2Location;
+  offset_t ID3v2Location;
   uint ID3v2OriginalSize;
 
-  long APELocation;
-  long APEFooterLocation;
+  offset_t APELocation;
+  offset_t APEFooterLocation;
   uint APEOriginalSize;
 
-  long ID3v1Location;
+  offset_t ID3v1Location;
 
   TagUnion tag;
 
@@ -368,7 +368,7 @@ void MPEG::File::setID3v2FrameFactory(const ID3v2::FrameFactory *factory)
   d->ID3v2FrameFactory = factory;
 }
 
-long MPEG::File::nextFrameOffset(long position)
+offset_t MPEG::File::nextFrameOffset(offset_t position)
 {
   bool foundLastSyncPattern = false;
 
@@ -394,13 +394,13 @@ long MPEG::File::nextFrameOffset(long position)
   }
 }
 
-long MPEG::File::previousFrameOffset(long position)
+offset_t MPEG::File::previousFrameOffset(offset_t position)
 {
   bool foundFirstSyncPattern = false;
   ByteVector buffer;
 
   while (position > 0) {
-    long size = ulong(position) < bufferSize() ? position : bufferSize();
+    uint size = position < static_cast<offset_t>(bufferSize()) ? static_cast<uint>(position) : bufferSize();
     position -= size;
 
     seek(position);
@@ -422,9 +422,9 @@ long MPEG::File::previousFrameOffset(long position)
   return -1;
 }
 
-long MPEG::File::firstFrameOffset()
+offset_t MPEG::File::firstFrameOffset()
 {
-  long position = 0;
+  offset_t position = 0;
 
   if(ID3v2Tag())
     position = d->ID3v2Location + ID3v2Tag()->header()->completeTagSize();
@@ -432,7 +432,7 @@ long MPEG::File::firstFrameOffset()
   return nextFrameOffset(position);
 }
 
-long MPEG::File::lastFrameOffset()
+offset_t MPEG::File::lastFrameOffset()
 {
   return previousFrameOffset(ID3v1Tag() ? d->ID3v1Location - 1 : length());
 }
@@ -503,7 +503,7 @@ void MPEG::File::read(bool readProperties, Properties::ReadStyle propertiesStyle
   ID3v1Tag(true);
 }
 
-long MPEG::File::findID3v2()
+offset_t MPEG::File::findID3v2()
 {
   // This method is based on the contents of TagLib::File::find(), but because
   // of some subtlteies -- specifically the need to look for the bit pattern of
@@ -513,7 +513,7 @@ long MPEG::File::findID3v2()
 
     // The position in the file that the current buffer starts at.
 
-    long bufferOffset = 0;
+    offset_t bufferOffset = 0;
     ByteVector buffer;
 
     // These variables are used to keep track of a partial match that happens at
@@ -525,7 +525,7 @@ long MPEG::File::findID3v2()
     // Save the location of the current read pointer.  We will restore the
     // position using seek() before all returns.
 
-    long originalPosition = tell();
+    offset_t originalPosition = tell();
 
     // Start the search at the beginning of the file.
 
@@ -614,11 +614,11 @@ long MPEG::File::findID3v2()
   return -1;
 }
 
-long MPEG::File::findID3v1()
+offset_t MPEG::File::findID3v1()
 {
   if(isValid()) {
     seek(-128, End);
-    long p = tell();
+    offset_t p = tell();
 
     if(readBlock(3) == ID3v1::Tag::fileIdentifier())
       return p;
@@ -631,7 +631,7 @@ void MPEG::File::findAPE()
   if(isValid()) {
     seek(d->hasID3v1 ? -160 : -32, End);
 
-    long p = tell();
+    offset_t p = tell();
 
     if(readBlock(8) == APE::Tag::fileIdentifier()) {
       d->APEFooterLocation = p;
diff --git a/taglib/mpeg/mpegfile.h b/taglib/mpeg/mpegfile.h
index f7b98364..b0d4a6db 100644
--- a/taglib/mpeg/mpegfile.h
+++ b/taglib/mpeg/mpegfile.h
@@ -282,24 +282,24 @@ namespace TagLib {
       /*!
        * Returns the position in the file of the first MPEG frame.
        */
-      long firstFrameOffset();
+      offset_t firstFrameOffset();
 
       /*!
        * Returns the position in the file of the next MPEG frame,
        * using the current position as start
        */
-      long nextFrameOffset(long position);
+      offset_t nextFrameOffset(offset_t position);
 
       /*!
        * Returns the position in the file of the previous MPEG frame,
        * using the current position as start
        */
-      long previousFrameOffset(long position);
+      offset_t previousFrameOffset(offset_t position);
 
       /*!
        * Returns the position in the file of the last MPEG frame.
        */
-      long lastFrameOffset();
+      offset_t lastFrameOffset();
 
       /*!
        * Returns whether or not the file on disk contains ID3v1 tag.
@@ -321,8 +321,8 @@ namespace TagLib {
       File &operator=(const File &);
 
       void read(bool readProperties, Properties::ReadStyle propertiesStyle);
-      long findID3v2();
-      long findID3v1();
+      offset_t findID3v2();
+      offset_t findID3v1();
       void findAPE();
 
       /*!
diff --git a/taglib/mpeg/mpegproperties.cpp b/taglib/mpeg/mpegproperties.cpp
index 3af95664..7fdc918b 100644
--- a/taglib/mpeg/mpegproperties.cpp
+++ b/taglib/mpeg/mpegproperties.cpp
@@ -151,7 +151,7 @@ void MPEG::Properties::read()
   // Since we've likely just looked for the ID3v1 tag, start at the end of the
   // file where we're least likely to have to have to move the disk head.
 
-  long last = d->file->lastFrameOffset();
+  offset_t last = d->file->lastFrameOffset();
 
   if(last < 0) {
     debug("MPEG::Properties::read() -- Could not find a valid last MPEG frame in the stream.");
@@ -161,7 +161,7 @@ void MPEG::Properties::read()
   d->file->seek(last);
   Header lastHeader(d->file->readBlock(4));
 
-  long first = d->file->firstFrameOffset();
+  offset_t first = d->file->firstFrameOffset();
 
   if(first < 0) {
     debug("MPEG::Properties::read() -- Could not find a valid first MPEG frame in the stream.");
@@ -170,7 +170,7 @@ void MPEG::Properties::read()
 
   if(!lastHeader.isValid()) {
 
-    long pos = last;
+    offset_t pos = last;
 
     while(pos > first) {
 
@@ -234,7 +234,7 @@ void MPEG::Properties::read()
     // Xing header.
 
     if(firstHeader.frameLength() > 0 && firstHeader.bitrate() > 0) {
-      int frames = (last - first) / firstHeader.frameLength() + 1;
+      int frames = static_cast<int>((last - first) / firstHeader.frameLength() + 1);
 
       d->length = int(float(firstHeader.frameLength() * frames) /
                       float(firstHeader.bitrate() * 125) + 0.5);
diff --git a/taglib/ogg/flac/oggflacfile.cpp b/taglib/ogg/flac/oggflacfile.cpp
index 9d9c303d..bf0d337e 100644
--- a/taglib/ogg/flac/oggflacfile.cpp
+++ b/taglib/ogg/flac/oggflacfile.cpp
@@ -56,8 +56,8 @@ public:
   Properties *properties;
   ByteVector streamInfoData;
   ByteVector xiphCommentData;
-  long streamStart;
-  long streamLength;
+  offset_t streamStart;
+  offset_t streamLength;
   bool scanned;
 
   bool hasXiphComment;
@@ -173,7 +173,7 @@ ByteVector Ogg::FLAC::File::xiphCommentData()
   return d->xiphCommentData;
 }
 
-long Ogg::FLAC::File::streamLength()
+offset_t Ogg::FLAC::File::streamLength()
 {
   scan();
   return d->streamLength;
@@ -190,7 +190,7 @@ void Ogg::FLAC::File::scan()
     return;
 
   int ipacket = 0;
-  long overhead = 0;
+  offset_t overhead = 0;
 
   ByteVector metadataHeader = packet(ipacket);
   if(metadataHeader.isNull())
diff --git a/taglib/ogg/flac/oggflacfile.h b/taglib/ogg/flac/oggflacfile.h
index 8558cfdf..2e08a55c 100644
--- a/taglib/ogg/flac/oggflacfile.h
+++ b/taglib/ogg/flac/oggflacfile.h
@@ -108,7 +108,7 @@ namespace TagLib {
        * Returns the length of the audio-stream, used by FLAC::Properties for
        * calculating the bitrate.
        */
-      long streamLength();
+      offset_t streamLength();
 
     private:
       File(const File &);
diff --git a/taglib/ogg/oggfile.cpp b/taglib/ogg/oggfile.cpp
index cc30f9ce..b8047070 100644
--- a/taglib/ogg/oggfile.cpp
+++ b/taglib/ogg/oggfile.cpp
@@ -157,7 +157,7 @@ const Ogg::PageHeader *Ogg::File::firstPageHeader()
   if(d->firstPageHeader)
     return d->firstPageHeader->isValid() ? d->firstPageHeader : 0;
 
-  long firstPageHeaderOffset = find("OggS");
+  offset_t firstPageHeaderOffset = find("OggS");
 
   if(firstPageHeaderOffset < 0)
     return 0;
@@ -171,7 +171,7 @@ const Ogg::PageHeader *Ogg::File::lastPageHeader()
   if(d->lastPageHeader)
     return d->lastPageHeader->isValid() ? d->lastPageHeader : 0;
 
-  long lastPageHeaderOffset = rfind("OggS");
+  offset_t lastPageHeaderOffset = rfind("OggS");
 
   if(lastPageHeaderOffset < 0)
     return 0;
@@ -224,7 +224,7 @@ Ogg::File::File(IOStream *stream) : TagLib::File(stream)
 
 bool Ogg::File::nextPage()
 {
-  long nextPageOffset;
+  offset_t nextPageOffset;
   int currentPacket;
 
   if(d->pages.isEmpty()) {
diff --git a/taglib/ogg/oggpage.cpp b/taglib/ogg/oggpage.cpp
index e5f767ec..86d788e5 100644
--- a/taglib/ogg/oggpage.cpp
+++ b/taglib/ogg/oggpage.cpp
@@ -35,7 +35,7 @@ using namespace TagLib;
 class Ogg::Page::PagePrivate
 {
 public:
-  PagePrivate(File *f = 0, long pageOffset = -1) :
+  PagePrivate(File *f = 0, offset_t pageOffset = -1) :
     file(f),
     fileOffset(pageOffset),
     packetOffset(0),
@@ -50,8 +50,8 @@ public:
   }
 
   File *file;
-  long fileOffset;
-  long packetOffset;
+  offset_t fileOffset;
+  offset_t packetOffset;
   int dataSize;
   List<int> packetSizes;
   PageHeader header;
@@ -63,7 +63,7 @@ public:
 // public members
 ////////////////////////////////////////////////////////////////////////////////
 
-Ogg::Page::Page(Ogg::File *file, long pageOffset)
+Ogg::Page::Page(Ogg::File *file, offset_t pageOffset)
 {
   d = new PagePrivate(file, pageOffset);
 }
@@ -73,7 +73,7 @@ Ogg::Page::~Page()
   delete d;
 }
 
-long Ogg::Page::fileOffset() const
+offset_t Ogg::Page::fileOffset() const
 {
   return d->fileOffset;
 }
diff --git a/taglib/ogg/oggpage.h b/taglib/ogg/oggpage.h
index e9f4840c..ff905913 100644
--- a/taglib/ogg/oggpage.h
+++ b/taglib/ogg/oggpage.h
@@ -55,14 +55,14 @@ namespace TagLib {
       /*!
        * Read an Ogg page from the \a file at the position \a pageOffset.
        */
-      Page(File *file, long pageOffset);
+      Page(File *file, offset_t pageOffset);
 
       virtual ~Page();
 
       /*!
        * Returns the page's position within the file (in bytes).
        */
-      long fileOffset() const;
+      offset_t fileOffset() const;
 
       /*!
        * Returns a pointer to the header for this page.  This pointer will become
diff --git a/taglib/ogg/oggpageheader.cpp b/taglib/ogg/oggpageheader.cpp
index f9608ab7..9ac88ef6 100644
--- a/taglib/ogg/oggpageheader.cpp
+++ b/taglib/ogg/oggpageheader.cpp
@@ -39,7 +39,7 @@ using namespace TagLib;
 class Ogg::PageHeader::PageHeaderPrivate
 {
 public:
-  PageHeaderPrivate(File *f, long pageOffset) :
+  PageHeaderPrivate(File *f, offset_t pageOffset) :
     file(f),
     fileOffset(pageOffset),
     isValid(false),
@@ -55,7 +55,7 @@ public:
     {}
 
   File *file;
-  long fileOffset;
+  offset_t fileOffset;
   bool isValid;
   List<int> packetSizes;
   bool firstPacketContinued;
@@ -73,7 +73,7 @@ public:
 // public members
 ////////////////////////////////////////////////////////////////////////////////
 
-Ogg::PageHeader::PageHeader(Ogg::File *file, long pageOffset)
+Ogg::PageHeader::PageHeader(Ogg::File *file, offset_t pageOffset)
 {
   d = new PageHeaderPrivate(file, pageOffset);
   if(file && pageOffset >= 0)
diff --git a/taglib/ogg/oggpageheader.h b/taglib/ogg/oggpageheader.h
index 742710a4..3cdec45b 100644
--- a/taglib/ogg/oggpageheader.h
+++ b/taglib/ogg/oggpageheader.h
@@ -52,7 +52,7 @@ namespace TagLib {
        * create a page with no (and as such, invalid) data that must be set
        * later.
        */
-      PageHeader(File *file = 0, long pageOffset = -1);
+      PageHeader(File *file = 0, offset_t pageOffset = -1);
 
       /*!
        * Deletes this instance of the PageHeader.
diff --git a/taglib/riff/rifffile.cpp b/taglib/riff/rifffile.cpp
index a38e1c40..2a0e433c 100644
--- a/taglib/riff/rifffile.cpp
+++ b/taglib/riff/rifffile.cpp
@@ -35,7 +35,7 @@ using namespace TagLib;
 struct Chunk
 {
   ByteVector name;
-  TagLib::uint offset;
+  offset_t offset;
   TagLib::uint size;
   char padding;
 };
@@ -103,7 +103,7 @@ TagLib::uint RIFF::File::chunkDataSize(uint i) const
   return d->chunks[i].size;
 }
 
-TagLib::uint RIFF::File::chunkOffset(uint i) const
+offset_t RIFF::File::chunkOffset(uint i) const
 {
   return d->chunks[i].offset;
 }
@@ -182,20 +182,25 @@ void RIFF::File::setChunkData(const ByteVector &name, const ByteVector &data, bo
   // Couldn't find an existing chunk, so let's create a new one.
 
   uint i =  d->chunks.size() - 1;
-  ulong offset = d->chunks[i].offset + d->chunks[i].size;
+  offset_t offset = d->chunks[i].offset + d->chunks[i].size;
 
   // First we update the global size
 
-  d->size += (offset & 1) + data.size() + 8;
+  d->size += static_cast<uint>(offset & 1) + data.size() + 8;
   insert(ByteVector::fromUInt(d->size, d->endianness == BigEndian), 4, 4);
 
   // Now add the chunk to the file
 
-  writeChunk(name, data, offset, std::max<long>(0, length() - offset), (offset & 1) ? 1 : 0);
+  writeChunk(
+    name, 
+    data, 
+    offset, 
+    static_cast<uint>(std::max<offset_t>(0, length() - offset)), 
+    static_cast<uint>(offset & 1));
 
   // And update our internal structure
 
-  if (offset & 1) {
+  if(offset & 1) {
     d->chunks[i].padding = 1;
     offset++;
   }
@@ -204,7 +209,7 @@ void RIFF::File::setChunkData(const ByteVector &name, const ByteVector &data, bo
   chunk.name = name;
   chunk.size = data.size();
   chunk.offset = offset + 8;
-  chunk.padding = (data.size() & 0x01) ? 1 : 0;
+  chunk.padding = static_cast<char>(data.size() & 1);
 
   d->chunks.push_back(chunk);
 }
@@ -282,8 +287,8 @@ void RIFF::File::read()
 
     // check padding
     chunk.padding = 0;
-    long uPosNotPadded = tell();
-    if((uPosNotPadded & 0x01) != 0) {
+    offset_t uPosNotPadded = tell();
+    if(uPosNotPadded & 1) {
       ByteVector iByte = readBlock(1);
       if((iByte.size() != 1) || (iByte[0] != 0)) {
         // not well formed, re-seek
@@ -299,7 +304,7 @@ void RIFF::File::read()
 }
 
 void RIFF::File::writeChunk(const ByteVector &name, const ByteVector &data,
-                            ulong offset, ulong replace, uint leadingPadding)
+                            offset_t offset, TagLib::uint replace, TagLib::uint leadingPadding)
 {
   ByteVector combined;
   if(leadingPadding) {
diff --git a/taglib/riff/rifffile.h b/taglib/riff/rifffile.h
index 274549ae..6e7dce3f 100644
--- a/taglib/riff/rifffile.h
+++ b/taglib/riff/rifffile.h
@@ -71,7 +71,7 @@ namespace TagLib {
       /*!
        * \return The offset within the file for the selected chunk number.
        */
-      uint chunkOffset(uint i) const;
+      offset_t chunkOffset(uint i) const;
 
       /*!
        * \return The size of the chunk data.
@@ -135,7 +135,7 @@ namespace TagLib {
 
       void read();
       void writeChunk(const ByteVector &name, const ByteVector &data,
-                      ulong offset, ulong replace = 0,
+                      offset_t offset, uint replace = 0,
                       uint leadingPadding = 0);
 
       class FilePrivate;
diff --git a/taglib/toolkit/taglib.h b/taglib/toolkit/taglib.h
index e941ca78..2c867da1 100755
--- a/taglib/toolkit/taglib.h
+++ b/taglib/toolkit/taglib.h
@@ -44,6 +44,17 @@
 
 #include <string>
 
+#ifndef _WIN32
+
+#  ifndef _LARGEFILE_SOURCE
+#    define _LARGEFILE_SOURCE
+#  endif
+
+#  define _FILE_OFFSET_BITS 64
+#  include <sys/types.h>
+
+#endif
+
 #ifdef __APPLE__
 #  include <libkern/OSAtomic.h>
 #  define TAGLIB_ATOMIC_MAC
@@ -83,6 +94,14 @@ namespace TagLib {
   typedef unsigned int   uint;
   typedef unsigned long  ulong;
 
+  // Offset or length type for I/O streams.  
+  // In Win32, always 64bit. Otherwise, equivalent to off_t.
+#ifdef _WIN32
+  typedef LONGLONG offset_t;
+#else
+  typedef off_t    offset_t;
+#endif
+
   /*!
    * Unfortunately std::wstring isn't defined on some systems, (i.e. GCC < 3)
    * so I'm providing something here that should be constant.
diff --git a/taglib/toolkit/tbytevectorstream.cpp b/taglib/toolkit/tbytevectorstream.cpp
index dc480a26..9a3ace03 100644
--- a/taglib/toolkit/tbytevectorstream.cpp
+++ b/taglib/toolkit/tbytevectorstream.cpp
@@ -28,9 +28,9 @@
 #include "tdebug.h"
 
 #include <stdio.h>
-#include <string.h>
-
+#include <stddef.h>
 #include <stdlib.h>
+#include <string.h>
 
 using namespace TagLib;
 
@@ -40,7 +40,7 @@ public:
   ByteVectorStreamPrivate(const ByteVector &data);
 
   ByteVector data;
-  long position;
+  offset_t position;
 };
 
 ByteVectorStream::ByteVectorStreamPrivate::ByteVectorStreamPrivate(const ByteVector &data) :
@@ -68,12 +68,12 @@ FileName ByteVectorStream::name() const
   return FileName(""); // XXX do we need a name?
 }
 
-ByteVector ByteVectorStream::readBlock(ulong length)
+ByteVector ByteVectorStream::readBlock(uint length)
 {
   if(length == 0)
     return ByteVector::null;
 
-  ByteVector v = d->data.mid(d->position, length);
+  ByteVector v = d->data.mid(static_cast<uint>(d->position), length);
   d->position += v.size();
   return v;
 }
@@ -81,14 +81,14 @@ ByteVector ByteVectorStream::readBlock(ulong length)
 void ByteVectorStream::writeBlock(const ByteVector &data)
 {
   uint size = data.size();
-  if(long(d->position + size) > length()) {
+  if(static_cast<offset_t>(d->position + size) > length())
     truncate(d->position + size);
-  }
+  
   memcpy(d->data.data() + d->position, data.data(), size);
   d->position += size;
 }
 
-void ByteVectorStream::insert(const ByteVector &data, ulong start, ulong replace)
+void ByteVectorStream::insert(const ByteVector &data, offset_t start, uint replace)
 {
   long sizeDiff = data.size() - replace;
   if(sizeDiff < 0) {
@@ -96,21 +96,27 @@ void ByteVectorStream::insert(const ByteVector &data, ulong start, ulong replace
   }
   else if(sizeDiff > 0) {
     truncate(length() + sizeDiff);
-    ulong readPosition = start + replace;
-    ulong writePosition = start + data.size();
-    memmove(d->data.data() + writePosition, d->data.data() + readPosition, length() - sizeDiff - readPosition);
+    offset_t readPosition  = start + replace;
+    offset_t writePosition = start + data.size();
+    memmove(
+      d->data.data() + static_cast<ptrdiff_t>(writePosition), 
+      d->data.data() + static_cast<ptrdiff_t>(readPosition), 
+      static_cast<size_t>(length() - sizeDiff - readPosition));
   }
   seek(start);
   writeBlock(data);
 }
 
-void ByteVectorStream::removeBlock(ulong start, ulong length)
+void ByteVectorStream::removeBlock(offset_t start, uint length)
 {
-  ulong readPosition = start + length;
-  ulong writePosition = start;
-  if(readPosition < ulong(ByteVectorStream::length())) {
-    ulong bytesToMove = ByteVectorStream::length() - readPosition;
-    memmove(d->data.data() + writePosition, d->data.data() + readPosition, bytesToMove);
+  offset_t readPosition  = start + length;
+  offset_t writePosition = start;
+  if(readPosition < ByteVectorStream::length()) {
+    size_t bytesToMove = static_cast<size_t>(ByteVectorStream::length() - readPosition);
+    memmove(
+      d->data.data() + static_cast<ptrdiff_t>(writePosition), 
+      d->data.data() + static_cast<ptrdiff_t>(readPosition), 
+      bytesToMove);
     writePosition += bytesToMove;
   }
   d->position = writePosition;
@@ -127,7 +133,7 @@ bool ByteVectorStream::isOpen() const
   return true;
 }
 
-void ByteVectorStream::seek(long offset, Position p)
+void ByteVectorStream::seek(offset_t offset, Position p)
 {
   switch(p) {
   case Beginning:
@@ -146,19 +152,19 @@ void ByteVectorStream::clear()
 {
 }
 
-long ByteVectorStream::tell() const
+offset_t ByteVectorStream::tell() const
 {
   return d->position;
 }
 
-long ByteVectorStream::length()
+offset_t ByteVectorStream::length()
 {
-  return d->data.size();
+  return static_cast<offset_t>(d->data.size());
 }
 
-void ByteVectorStream::truncate(long length)
+void ByteVectorStream::truncate(offset_t length)
 {
-  d->data.resize(length);
+  d->data.resize(static_cast<uint>(length));
 }
 
 ByteVector *ByteVectorStream::data()
diff --git a/taglib/toolkit/tbytevectorstream.h b/taglib/toolkit/tbytevectorstream.h
index 456b854e..7b455c82 100644
--- a/taglib/toolkit/tbytevectorstream.h
+++ b/taglib/toolkit/tbytevectorstream.h
@@ -61,7 +61,7 @@ namespace TagLib {
     /*!
      * Reads a block of size \a length at the current get pointer.
      */
-    ByteVector readBlock(ulong length);
+    ByteVector readBlock(uint length);
 
     /*!
      * Attempts to write the block \a data at the current get pointer.  If the
@@ -81,7 +81,7 @@ namespace TagLib {
      * \note This method is slow since it requires rewriting all of the file
      * after the insertion point.
      */
-    void insert(const ByteVector &data, ulong start = 0, ulong replace = 0);
+    void insert(const ByteVector &data, offset_t start = 0, uint replace = 0);
 
     /*!
      * Removes a block of the file starting a \a start and continuing for
@@ -90,7 +90,7 @@ namespace TagLib {
      * \note This method is slow since it involves rewriting all of the file
      * after the removed portion.
      */
-    void removeBlock(ulong start = 0, ulong length = 0);
+    void removeBlock(offset_t start = 0, uint length = 0);
 
     /*!
      * Returns true if the file is read only (or if the file can not be opened).
@@ -109,7 +109,7 @@ namespace TagLib {
      *
      * \see Position
      */
-    void seek(long offset, Position p = Beginning);
+    void seek(offset_t offset, Position p = Beginning);
 
     /*!
      * Reset the end-of-file and error flags on the file.
@@ -119,17 +119,17 @@ namespace TagLib {
     /*!
      * Returns the current offset within the file.
      */
-    long tell() const;
+    offset_t tell() const;
 
     /*!
      * Returns the length of the file.
      */
-    long length();
+    offset_t length();
 
     /*!
      * Truncates the file to a \a length.
      */
-    void truncate(long length);
+    void truncate(offset_t length);
 
     ByteVector *data();
 
diff --git a/taglib/toolkit/tfile.cpp b/taglib/toolkit/tfile.cpp
index e6062199..7eac9f58 100644
--- a/taglib/toolkit/tfile.cpp
+++ b/taglib/toolkit/tfile.cpp
@@ -132,7 +132,7 @@ PropertyMap File::setProperties(const PropertyMap &properties)
   return tag()->setProperties(properties);
 }
 
-ByteVector File::readBlock(ulong length)
+ByteVector File::readBlock(uint length)
 {
   return d->stream->readBlock(length);
 }
@@ -142,14 +142,14 @@ void File::writeBlock(const ByteVector &data)
   d->stream->writeBlock(data);
 }
 
-long File::find(const ByteVector &pattern, long fromOffset, const ByteVector &before)
+offset_t File::find(const ByteVector &pattern, offset_t fromOffset, const ByteVector &before)
 {
   if(!d->stream || pattern.size() > d->bufferSize)
       return -1;
 
   // The position in the file that the current buffer starts at.
 
-  long bufferOffset = fromOffset;
+  offset_t bufferOffset = fromOffset;
   ByteVector buffer;
 
   // These variables are used to keep track of a partial match that happens at
@@ -161,7 +161,7 @@ long File::find(const ByteVector &pattern, long fromOffset, const ByteVector &be
   // Save the location of the current read pointer.  We will restore the
   // position using seek() before all returns.
 
-  long originalPosition = tell();
+  offset_t originalPosition = tell();
 
   // Start the search at the offset.
 
@@ -238,7 +238,7 @@ long File::find(const ByteVector &pattern, long fromOffset, const ByteVector &be
 }
 
 
-long File::rfind(const ByteVector &pattern, long fromOffset, const ByteVector &before)
+offset_t File::rfind(const ByteVector &pattern, offset_t fromOffset, const ByteVector &before)
 {
   if(!d->stream || pattern.size() > d->bufferSize)
       return -1;
@@ -258,11 +258,11 @@ long File::rfind(const ByteVector &pattern, long fromOffset, const ByteVector &b
   // Save the location of the current read pointer.  We will restore the
   // position using seek() before all returns.
 
-  long originalPosition = tell();
+  offset_t originalPosition = tell();
 
   // Start the search at the offset.
 
-  long bufferOffset;
+  offset_t bufferOffset;
   if(fromOffset == 0) {
     seek(-1 * int(d->bufferSize), End);
     bufferOffset = tell();
@@ -306,12 +306,12 @@ long File::rfind(const ByteVector &pattern, long fromOffset, const ByteVector &b
   return -1;
 }
 
-void File::insert(const ByteVector &data, ulong start, ulong replace)
+void File::insert(const ByteVector &data, offset_t start, uint replace)
 {
   d->stream->insert(data, start, replace);
 }
 
-void File::removeBlock(ulong start, ulong length)
+void File::removeBlock(offset_t start, uint length)
 {
   d->stream->removeBlock(start, length);
 }
@@ -331,12 +331,12 @@ bool File::isValid() const
   return isOpen() && d->valid;
 }
 
-void File::seek(long offset, Position p)
+void File::seek(offset_t offset, Position p)
 {
   d->stream->seek(offset, IOStream::Position(p));
 }
 
-void File::truncate(long length)
+void File::truncate(offset_t length)
 {
   d->stream->truncate(length);
 }
@@ -346,12 +346,12 @@ void File::clear()
   d->stream->clear();
 }
 
-long File::tell() const
+offset_t File::tell() const
 {
   return d->stream->tell();
 }
 
-long File::length()
+offset_t File::length()
 {
   return d->stream->length();
 }
diff --git a/taglib/toolkit/tfile.h b/taglib/toolkit/tfile.h
index 1dfab498..3194f62d 100644
--- a/taglib/toolkit/tfile.h
+++ b/taglib/toolkit/tfile.h
@@ -128,7 +128,7 @@ namespace TagLib {
     /*!
      * Reads a block of size \a length at the current get pointer.
      */
-    ByteVector readBlock(ulong length);
+    ByteVector readBlock(uint length);
 
     /*!
      * Attempts to write the block \a data at the current get pointer.  If the
@@ -153,8 +153,8 @@ namespace TagLib {
      * \note This has the practial limitation that \a pattern can not be longer
      * than the buffer size used by readBlock().  Currently this is 1024 bytes.
      */
-    long find(const ByteVector &pattern,
-              long fromOffset = 0,
+    offset_t find(const ByteVector &pattern,
+              offset_t fromOffset = 0,
               const ByteVector &before = ByteVector::null);
 
     /*!
@@ -169,8 +169,8 @@ namespace TagLib {
      * \note This has the practial limitation that \a pattern can not be longer
      * than the buffer size used by readBlock().  Currently this is 1024 bytes.
      */
-    long rfind(const ByteVector &pattern,
-               long fromOffset = 0,
+    offset_t rfind(const ByteVector &pattern,
+               offset_t fromOffset = 0,
                const ByteVector &before = ByteVector::null);
 
     /*!
@@ -180,7 +180,7 @@ namespace TagLib {
      * \note This method is slow since it requires rewriting all of the file
      * after the insertion point.
      */
-    void insert(const ByteVector &data, ulong start = 0, ulong replace = 0);
+    void insert(const ByteVector &data, offset_t start = 0, uint replace = 0);
 
     /*!
      * Removes a block of the file starting a \a start and continuing for
@@ -189,7 +189,7 @@ namespace TagLib {
      * \note This method is slow since it involves rewriting all of the file
      * after the removed portion.
      */
-    void removeBlock(ulong start = 0, ulong length = 0);
+    void removeBlock(offset_t start = 0, uint length = 0);
 
     /*!
      * Returns true if the file is read only (or if the file can not be opened).
@@ -213,7 +213,7 @@ namespace TagLib {
      *
      * \see Position
      */
-    void seek(long offset, Position p = Beginning);
+    void seek(offset_t offset, Position p = Beginning);
 
     /*!
      * Reset the end-of-file and error flags on the file.
@@ -223,12 +223,12 @@ namespace TagLib {
     /*!
      * Returns the current offset within the file.
      */
-    long tell() const;
+    offset_t tell() const;
 
     /*!
      * Returns the length of the file.
      */
-    long length();
+    offset_t length();
 
     /*!
      * Returns true if \a file can be opened for reading.  If the file does not
@@ -276,7 +276,7 @@ namespace TagLib {
     /*!
      * Truncates the file to a \a length.
      */
-    void truncate(long length);
+    void truncate(offset_t length);
 
     /*!
      * Returns the buffer size that is used for internal buffering.
diff --git a/taglib/toolkit/tfilestream.cpp b/taglib/toolkit/tfilestream.cpp
index 16efb579..69bd1291 100644
--- a/taglib/toolkit/tfilestream.cpp
+++ b/taglib/toolkit/tfilestream.cpp
@@ -27,19 +27,16 @@
 #include "tstring.h"
 #include "tdebug.h"
 
-#include <stdio.h>
 #include <string.h>
 #include <sys/stat.h>
 
-#ifdef _WIN32
-# include <wchar.h>
-# include <windows.h>
-# include <io.h>
-#else
+#ifndef _WIN32
+# include <stdio.h>
 # include <unistd.h>
 #endif
 
 #include <stdlib.h>
+#include <limits>
 
 using namespace TagLib;
 
@@ -114,7 +111,7 @@ public:
   FileNameHandle name;
 
   bool readOnly;
-  ulong size;
+  offset_t size;
   static const uint bufferSize = 1024;
 };
 
@@ -170,7 +167,7 @@ FileName FileStream::name() const
   return d->name;
 }
 
-ByteVector FileStream::readBlock(ulong length)
+ByteVector FileStream::readBlock(uint length)
 {
   if(!d->file) {
     debug("FileStream::readBlock() -- Invalid File");
@@ -181,14 +178,14 @@ ByteVector FileStream::readBlock(ulong length)
     return ByteVector::null;
 
   if(length > FileStreamPrivate::bufferSize &&
-     length > ulong(FileStream::length()))
+     static_cast<offset_t>(length) > FileStream::length())
   {
-    length = FileStream::length();
+    length = static_cast<uint>(FileStream::length());
   }
 
-  ByteVector v(static_cast<uint>(length));
-  const int count = fread(v.data(), sizeof(char), length, d->file);
-  v.resize(count);
+  ByteVector v(length);
+  const size_t count = fread(v.data(), sizeof(char), length, d->file);
+  v.resize(static_cast<uint>(count));
   return v;
 }
 
@@ -205,7 +202,7 @@ void FileStream::writeBlock(const ByteVector &data)
   fwrite(data.data(), sizeof(char), data.size(), d->file);
 }
 
-void FileStream::insert(const ByteVector &data, ulong start, ulong replace)
+void FileStream::insert(const ByteVector &data, offset_t start, uint replace)
 {
   if(!d->file)
     return;
@@ -232,15 +229,15 @@ void FileStream::insert(const ByteVector &data, ulong start, ulong replace)
   // the *differnce* in the tag sizes.  We want to avoid overwriting parts
   // that aren't yet in memory, so this is necessary.
 
-  ulong bufferLength = bufferSize();
+  size_t bufferLength = bufferSize();
 
   while(data.size() - replace > bufferLength)
     bufferLength += bufferSize();
 
   // Set where to start the reading and writing.
 
-  long readPosition = start + replace;
-  long writePosition = start;
+  offset_t readPosition  = start + replace;
+  offset_t writePosition = start;
 
   ByteVector buffer;
   ByteVector aboutToOverwrite(static_cast<uint>(bufferLength));
@@ -252,7 +249,7 @@ void FileStream::insert(const ByteVector &data, ulong start, ulong replace)
   // That's a bit slower than using char *'s so, we're only doing it here.
 
   seek(readPosition);
-  int bytesRead = fread(aboutToOverwrite.data(), sizeof(char), bufferLength, d->file);
+  size_t bytesRead = fread(aboutToOverwrite.data(), sizeof(char), bufferLength, d->file);
   readPosition += bufferLength;
 
   seek(writePosition);
@@ -281,7 +278,7 @@ void FileStream::insert(const ByteVector &data, ulong start, ulong replace)
     // Check to see if we just read the last block.  We need to call clear()
     // if we did so that the last write succeeds.
 
-    if(ulong(bytesRead) < bufferLength)
+    if(bytesRead < bufferLength)
       clear();
 
     // Seek to the write position and write our buffer.  Increment the
@@ -301,21 +298,24 @@ void FileStream::insert(const ByteVector &data, ulong start, ulong replace)
 
     bufferLength = bytesRead;
   }
+
+  // Clear the file size cache. 
+  d->size = 0;
 }
 
-void FileStream::removeBlock(ulong start, ulong length)
+void FileStream::removeBlock(offset_t start, uint length)
 {
   if(!d->file)
     return;
 
-  ulong bufferLength = bufferSize();
+  size_t bufferLength = bufferSize();
 
-  long readPosition = start + length;
-  long writePosition = start;
+  offset_t readPosition  = start + length;
+  offset_t writePosition = start;
 
   ByteVector buffer(static_cast<uint>(bufferLength));
 
-  ulong bytesRead = 1;
+  size_t bytesRead = 1;
 
   while(bytesRead != 0) {
     seek(readPosition);
@@ -345,7 +345,7 @@ bool FileStream::isOpen() const
   return (d->file != NULL);
 }
 
-void FileStream::seek(long offset, Position p)
+void FileStream::seek(offset_t offset, Position p)
 {
   if(!d->file) {
     debug("File::seek() -- trying to seek in a file that isn't opened.");
@@ -367,7 +367,9 @@ void FileStream::seek(long offset, Position p)
     break;
   }
 
-  SetFilePointer(d->file, offset, NULL, whence);
+  LARGE_INTEGER largeOffset = {};
+  largeOffset.QuadPart = offset;
+  SetFilePointerEx(d->file, largeOffset, nullptr, whence);
 
 #else
 
@@ -384,7 +386,15 @@ void FileStream::seek(long offset, Position p)
     break;
   }
 
-  fseek(d->file, offset, whence);
+# ifdef _LARGEFILE_SOURCE
+
+  fseeko(d->file, offset, whence);
+
+# else
+
+  fseek(d->file, static_cast<long>(offset), whence);
+
+# endif 
 
 #endif
 }
@@ -402,20 +412,33 @@ void FileStream::clear()
 #endif
 }
 
-long FileStream::tell() const
+offset_t FileStream::tell() const
 {
 #ifdef _WIN32
 
-  return (long)SetFilePointer(d->file, 0, NULL, FILE_CURRENT);
+  LARGE_INTEGER largeOffset = {};
+  LARGE_INTEGER newPointer;
+
+  SetFilePointerEx(d->file, largeOffset, &newPointer, FILE_CURRENT);
+
+  return newPointer.QuadPart;
 
 #else
 
-  return ftell(d->file);
+# ifdef _LARGEFILE_SOURCE
+
+  return ftello(d->file);
+
+# else
+
+  return static_cast<offset_t>(ftell(d->file));
+
+# endif 
 
 #endif
 }
 
-long FileStream::length()
+offset_t FileStream::length()
 {
   // Do some caching in case we do multiple calls.
 
@@ -425,31 +448,31 @@ long FileStream::length()
   if(!d->file)
     return 0;
 
-  long curpos = tell();
+  offset_t currentPosition = tell();
 
   seek(0, End);
-  long endpos = tell();
+  offset_t endPosition = tell();
 
-  seek(curpos, Beginning);
+  seek(currentPosition, Beginning);
 
-  d->size = endpos;
-  return endpos;
+  d->size = endPosition;
+  return endPosition;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // protected members
 ////////////////////////////////////////////////////////////////////////////////
 
-void FileStream::truncate(long length)
+void FileStream::truncate(offset_t length)
 {
 #ifdef _WIN32
 
-  long currentPos = tell();
+  offset_t currentPosition = tell();
 
   seek(length);
   SetEndOfFile(d->file);
 
-  seek(currentPos);
+  seek(currentPosition);
 
 #else
 
diff --git a/taglib/toolkit/tfilestream.h b/taglib/toolkit/tfilestream.h
index fa113b73..d3a6179e 100644
--- a/taglib/toolkit/tfilestream.h
+++ b/taglib/toolkit/tfilestream.h
@@ -67,7 +67,7 @@ namespace TagLib {
     /*!
      * Reads a block of size \a length at the current get pointer.
      */
-    ByteVector readBlock(ulong length);
+    ByteVector readBlock(uint length);
 
     /*!
      * Attempts to write the block \a data at the current get pointer.  If the
@@ -87,7 +87,7 @@ namespace TagLib {
      * \note This method is slow since it requires rewriting all of the file
      * after the insertion point.
      */
-    void insert(const ByteVector &data, ulong start = 0, ulong replace = 0);
+    void insert(const ByteVector &data, offset_t start = 0, uint replace = 0);
 
     /*!
      * Removes a block of the file starting a \a start and continuing for
@@ -96,7 +96,7 @@ namespace TagLib {
      * \note This method is slow since it involves rewriting all of the file
      * after the removed portion.
      */
-    void removeBlock(ulong start = 0, ulong length = 0);
+    void removeBlock(offset_t start = 0, uint length = 0);
 
     /*!
      * Returns true if the file is read only (or if the file can not be opened).
@@ -115,7 +115,7 @@ namespace TagLib {
      *
      * \see Position
      */
-    void seek(long offset, Position p = Beginning);
+    void seek(offset_t offset, Position p = Beginning);
 
     /*!
      * Reset the end-of-file and error flags on the file.
@@ -125,17 +125,17 @@ namespace TagLib {
     /*!
      * Returns the current offset within the file.
      */
-    long tell() const;
+    offset_t tell() const;
 
     /*!
      * Returns the length of the file.
      */
-    long length();
+    offset_t length();
 
     /*!
      * Truncates the file to a \a length.
      */
-    void truncate(long length);
+    void truncate(offset_t length);
 
   protected:
 
diff --git a/taglib/toolkit/tiostream.h b/taglib/toolkit/tiostream.h
index 3e7de22a..ac7ad7fc 100644
--- a/taglib/toolkit/tiostream.h
+++ b/taglib/toolkit/tiostream.h
@@ -80,7 +80,7 @@ namespace TagLib {
     /*!
      * Reads a block of size \a length at the current get pointer.
      */
-    virtual ByteVector readBlock(ulong length) = 0;
+    virtual ByteVector readBlock(uint length) = 0;
 
     /*!
      * Attempts to write the block \a data at the current get pointer.  If the
@@ -100,7 +100,7 @@ namespace TagLib {
      * \note This method is slow since it requires rewriting all of the file
      * after the insertion point.
      */
-    virtual void insert(const ByteVector &data, ulong start = 0, ulong replace = 0) = 0;
+    virtual void insert(const ByteVector &data, offset_t start = 0, uint replace = 0) = 0;
 
     /*!
      * Removes a block of the file starting a \a start and continuing for
@@ -109,7 +109,7 @@ namespace TagLib {
      * \note This method is slow since it involves rewriting all of the file
      * after the removed portion.
      */
-    virtual void removeBlock(ulong start = 0, ulong length = 0) = 0;
+    virtual void removeBlock(offset_t start = 0, uint length = 0) = 0;
 
     /*!
      * Returns true if the file is read only (or if the file can not be opened).
@@ -128,7 +128,7 @@ namespace TagLib {
      *
      * \see Position
      */
-    virtual void seek(long offset, Position p = Beginning) = 0;
+    virtual void seek(offset_t offset, Position p = Beginning) = 0;
 
     /*!
      * Reset the end-of-stream and error flags on the stream.
@@ -138,17 +138,17 @@ namespace TagLib {
     /*!
      * Returns the current offset within the stream.
      */
-    virtual long tell() const = 0;
+    virtual offset_t tell() const = 0;
 
     /*!
      * Returns the length of the stream.
      */
-    virtual long length() = 0;
+    virtual offset_t length() = 0;
 
     /*!
      * Truncates the stream to a \a length.
      */
-    virtual void truncate(long length) = 0;
+    virtual void truncate(offset_t length) = 0;
 
   private:
     IOStream(const IOStream &);
diff --git a/taglib/trueaudio/trueaudiofile.cpp b/taglib/trueaudio/trueaudiofile.cpp
index 9efc6e9d..06879447 100644
--- a/taglib/trueaudio/trueaudiofile.cpp
+++ b/taglib/trueaudio/trueaudiofile.cpp
@@ -64,10 +64,10 @@ public:
   }
 
   const ID3v2::FrameFactory *ID3v2FrameFactory;
-  long ID3v2Location;
+  offset_t ID3v2Location;
   uint ID3v2OriginalSize;
 
-  long ID3v1Location;
+  offset_t ID3v1Location;
 
   TagUnion tag;
 
@@ -284,13 +284,13 @@ void TrueAudio::File::read(bool readProperties, Properties::ReadStyle /* propert
   }
 }
 
-long TrueAudio::File::findID3v1()
+offset_t TrueAudio::File::findID3v1()
 {
   if(!isValid())
     return -1;
 
   seek(-128, End);
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(3) == ID3v1::Tag::fileIdentifier())
     return p;
@@ -298,7 +298,7 @@ long TrueAudio::File::findID3v1()
   return -1;
 }
 
-long TrueAudio::File::findID3v2()
+offset_t TrueAudio::File::findID3v2()
 {
   if(!isValid())
     return -1;
diff --git a/taglib/trueaudio/trueaudiofile.h b/taglib/trueaudio/trueaudiofile.h
index e3e1fe62..8b8b0c05 100644
--- a/taglib/trueaudio/trueaudiofile.h
+++ b/taglib/trueaudio/trueaudiofile.h
@@ -206,8 +206,8 @@ namespace TagLib {
 
       void read(bool readProperties, Properties::ReadStyle propertiesStyle);
       void scan();
-      long findID3v1();
-      long findID3v2();
+      offset_t findID3v1();
+      offset_t findID3v2();
 
       class FilePrivate;
       FilePrivate *d;
diff --git a/taglib/trueaudio/trueaudioproperties.cpp b/taglib/trueaudio/trueaudioproperties.cpp
index 9b251ff1..43423d9c 100644
--- a/taglib/trueaudio/trueaudioproperties.cpp
+++ b/taglib/trueaudio/trueaudioproperties.cpp
@@ -39,7 +39,7 @@ using namespace TagLib;
 class TrueAudio::Properties::PropertiesPrivate
 {
 public:
-  PropertiesPrivate(const ByteVector &d, long length, ReadStyle s) :
+  PropertiesPrivate(const ByteVector &d, offset_t length, ReadStyle s) :
     data(d),
     streamLength(length),
     style(s),
@@ -52,7 +52,7 @@ public:
     sampleFrames(0) {}
 
   ByteVector data;
-  long streamLength;
+  offset_t streamLength;
   ReadStyle style;
   int version;
   int length;
@@ -67,7 +67,7 @@ public:
 // public members
 ////////////////////////////////////////////////////////////////////////////////
 
-TrueAudio::Properties::Properties(const ByteVector &data, long streamLength, ReadStyle style) : AudioProperties(style)
+TrueAudio::Properties::Properties(const ByteVector &data, offset_t streamLength, ReadStyle style) : AudioProperties(style)
 {
   d = new PropertiesPrivate(data, streamLength, style);
   read();
@@ -145,6 +145,6 @@ void TrueAudio::Properties::read()
     d->sampleFrames = d->data.mid(pos, 4).toUInt(false);
     d->length = d->sampleRate > 0 ? d->sampleFrames / d->sampleRate : 0;
 
-    d->bitrate = d->length > 0 ? ((d->streamLength * 8L) / d->length) / 1000 : 0;
+    d->bitrate = d->length > 0 ? static_cast<int>(d->streamLength * 8L / d->length / 1000) : 0;
   }
 }
diff --git a/taglib/trueaudio/trueaudioproperties.h b/taglib/trueaudio/trueaudioproperties.h
index 126b6788..67354696 100644
--- a/taglib/trueaudio/trueaudioproperties.h
+++ b/taglib/trueaudio/trueaudioproperties.h
@@ -54,7 +54,7 @@ namespace TagLib {
        * Create an instance of TrueAudio::Properties with the data read from the
        * ByteVector \a data.
        */
-      Properties(const ByteVector &data, long streamLength, ReadStyle style = Average);
+      Properties(const ByteVector &data, offset_t streamLength, ReadStyle style = Average);
 
       /*!
        * Destroys this TrueAudio::Properties instance.
diff --git a/taglib/wavpack/wavpackfile.cpp b/taglib/wavpack/wavpackfile.cpp
index 49f7923e..8fe78830 100644
--- a/taglib/wavpack/wavpackfile.cpp
+++ b/taglib/wavpack/wavpackfile.cpp
@@ -62,10 +62,10 @@ public:
     delete properties;
   }
 
-  long APELocation;
+  offset_t APELocation;
   uint APESize;
 
-  long ID3v1Location;
+  offset_t ID3v1Location;
 
   TagUnion tag;
 
@@ -261,7 +261,7 @@ void WavPack::File::read(bool readProperties, Properties::ReadStyle /* propertie
   }
 }
 
-long WavPack::File::findAPE()
+offset_t WavPack::File::findAPE()
 {
   if(!isValid())
     return -1;
@@ -271,7 +271,7 @@ long WavPack::File::findAPE()
   else
     seek(-32, End);
 
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(8) == APE::Tag::fileIdentifier())
     return p;
@@ -279,13 +279,13 @@ long WavPack::File::findAPE()
   return -1;
 }
 
-long WavPack::File::findID3v1()
+offset_t WavPack::File::findID3v1()
 {
   if(!isValid())
     return -1;
 
   seek(-128, End);
-  long p = tell();
+  offset_t p = tell();
 
   if(readBlock(3) == ID3v1::Tag::fileIdentifier())
     return p;
diff --git a/taglib/wavpack/wavpackfile.h b/taglib/wavpack/wavpackfile.h
index 5bbbc65a..cb0dfab9 100644
--- a/taglib/wavpack/wavpackfile.h
+++ b/taglib/wavpack/wavpackfile.h
@@ -177,8 +177,8 @@ namespace TagLib {
 
       void read(bool readProperties, Properties::ReadStyle propertiesStyle);
       void scan();
-      long findID3v1();
-      long findAPE();
+      offset_t findID3v1();
+      offset_t findAPE();
 
       class FilePrivate;
       FilePrivate *d;
diff --git a/taglib/wavpack/wavpackproperties.cpp b/taglib/wavpack/wavpackproperties.cpp
index 1715f425..73d914dc 100644
--- a/taglib/wavpack/wavpackproperties.cpp
+++ b/taglib/wavpack/wavpackproperties.cpp
@@ -38,7 +38,7 @@ using namespace TagLib;
 class WavPack::Properties::PropertiesPrivate
 {
 public:
-  PropertiesPrivate(const ByteVector &d, long length, ReadStyle s) :
+  PropertiesPrivate(const ByteVector &d, offset_t length, ReadStyle s) :
     data(d),
     streamLength(length),
     style(s),
@@ -52,7 +52,7 @@ public:
     file(0) {}
 
   ByteVector data;
-  long streamLength;
+  offset_t streamLength;
   ReadStyle style;
   int length;
   int bitrate;
@@ -68,13 +68,13 @@ public:
 // public members
 ////////////////////////////////////////////////////////////////////////////////
 
-WavPack::Properties::Properties(const ByteVector &data, long streamLength, ReadStyle style) : AudioProperties(style)
+WavPack::Properties::Properties(const ByteVector &data, offset_t streamLength, ReadStyle style) : AudioProperties(style)
 {
   d = new PropertiesPrivate(data, streamLength, style);
   read();
 }
 
-WavPack::Properties::Properties(File *file, long streamLength, ReadStyle style) : AudioProperties(style)
+WavPack::Properties::Properties(File *file, offset_t streamLength, ReadStyle style) : AudioProperties(style)
 {
   ByteVector data = file->readBlock(32);
   d = new PropertiesPrivate(data, streamLength, style);
@@ -170,14 +170,14 @@ void WavPack::Properties::read()
   d->length = d->sampleRate > 0 ? (samples + (d->sampleRate / 2)) / d->sampleRate : 0;
   d->sampleFrames = samples;
 
-  d->bitrate = d->length > 0 ? ((d->streamLength * 8L) / d->length) / 1000 : 0;
+  d->bitrate = d->length > 0 ? static_cast<int>(d->streamLength * 8L / d->length / 1000) : 0;
 }
 
 unsigned int WavPack::Properties::seekFinalIndex()
 {
   ByteVector blockID("wvpk", 4);
 
-  long offset = d->streamLength;
+  offset_t offset = d->streamLength;
   while(offset > 0) {
     offset = d->file->rfind(blockID, offset);
     if(offset == -1)
diff --git a/taglib/wavpack/wavpackproperties.h b/taglib/wavpack/wavpackproperties.h
index bd2209da..0766b422 100644
--- a/taglib/wavpack/wavpackproperties.h
+++ b/taglib/wavpack/wavpackproperties.h
@@ -58,13 +58,13 @@ namespace TagLib {
        * \deprecated This constructor will be dropped in favor of the one below
        * in a future version.
        */
-      Properties(const ByteVector &data, long streamLength, ReadStyle style = Average);
+      Properties(const ByteVector &data, offset_t streamLength, ReadStyle style = Average);
 
       /*!
        * Create an instance of WavPack::Properties.
        */
       // BIC: merge with the above constructor
-      Properties(File *file, long streamLength, ReadStyle style = Average);
+      Properties(File *file, offset_t streamLength, ReadStyle style = Average);
 
       /*!
        * Destroys this WavPack::Properties instance.