diff --git a/taglib/ape/apetag.cpp b/taglib/ape/apetag.cpp
index ef3c3cd0..6c5c3b9b 100644
--- a/taglib/ape/apetag.cpp
+++ b/taglib/ape/apetag.cpp
@@ -216,7 +216,7 @@ void APE::Tag::read()
     d->file->seek(d->tagOffset);
     d->footer.setData(d->file->readBlock(Footer::size()));
 
-    if(d->footer.tagSize() == 0 ||
+    if(d->footer.tagSize() <= Footer::size() ||
        d->footer.tagSize() > uint(d->file->length()))
       return;
 
diff --git a/taglib/toolkit/tbytevector.cpp b/taglib/toolkit/tbytevector.cpp
index 26dd18cb..488d4773 100644
--- a/taglib/toolkit/tbytevector.cpp
+++ b/taglib/toolkit/tbytevector.cpp
@@ -321,7 +321,9 @@ ByteVector &ByteVector::setData(const char *data, uint length)
   detach();
 
   resize(length);
-  ::memcpy(DATA(d), data, length);
+
+  if(length > 0)
+    ::memcpy(DATA(d), data, length);
 
   return *this;
 }
@@ -334,12 +336,12 @@ ByteVector &ByteVector::setData(const char *data)
 char *ByteVector::data()
 {
   detach();
-  return DATA(d);
+  return size() > 0 ? DATA(d) : 0;
 }
 
 const char *ByteVector::data() const
 {
-  return DATA(d);
+  return size() > 0 ? DATA(d) : 0;
 }
 
 ByteVector ByteVector::mid(uint index, uint length) const
diff --git a/taglib/toolkit/tfile.cpp b/taglib/toolkit/tfile.cpp
index 2fa76077..a058763e 100644
--- a/taglib/toolkit/tfile.cpp
+++ b/taglib/toolkit/tfile.cpp
@@ -108,6 +108,9 @@ ByteVector File::readBlock(ulong length)
     return ByteVector::null;
   }
 
+  if(length == 0)
+    return ByteVector::null;
+
   if(length > FilePrivate::bufferSize &&
      length > ulong(File::length()))
   {