diff --git a/taglib/it/itproperties.h b/taglib/it/itproperties.h
index d624f887..3a6e346a 100644
--- a/taglib/it/itproperties.h
+++ b/taglib/it/itproperties.h
@@ -32,7 +32,6 @@
 namespace TagLib {
   namespace IT {
     class TAGLIB_EXPORT Properties : public AudioProperties {
-      friend class File;
     public:
       /*! Flag bits. */
       enum {
diff --git a/taglib/mod/modproperties.h b/taglib/mod/modproperties.h
index 78de8158..1581a076 100644
--- a/taglib/mod/modproperties.h
+++ b/taglib/mod/modproperties.h
@@ -50,8 +50,6 @@ namespace TagLib {
       void setLengthInPatterns(unsigned char lengthInPatterns);
 
     private:
-      friend class File;
-
       Properties(const Properties&) = delete;
       Properties &operator=(const Properties&) = delete;
 
diff --git a/taglib/s3m/s3mproperties.h b/taglib/s3m/s3mproperties.h
index 9136cced..a3b76079 100644
--- a/taglib/s3m/s3mproperties.h
+++ b/taglib/s3m/s3mproperties.h
@@ -32,7 +32,6 @@
 namespace TagLib {
   namespace S3M {
     class TAGLIB_EXPORT Properties : public AudioProperties {
-      friend class File;
     public:
       /*! Flag bits. */
       enum {
diff --git a/taglib/toolkit/tfilestream.cpp b/taglib/toolkit/tfilestream.cpp
index 38190186..458f228e 100644
--- a/taglib/toolkit/tfilestream.cpp
+++ b/taglib/toolkit/tfilestream.cpp
@@ -58,7 +58,7 @@ namespace
 #endif
   }
 
-  FileHandle openFile(const int fileDescriptor, bool readOnly)
+  FileHandle openFile([[maybe_unused]] const int fileDescriptor, [[maybe_unused]] bool readOnly)
   {
     return InvalidFileHandle;
   }
diff --git a/taglib/toolkit/tzlib.cpp b/taglib/toolkit/tzlib.cpp
index a463edcf..82e161f5 100644
--- a/taglib/toolkit/tzlib.cpp
+++ b/taglib/toolkit/tzlib.cpp
@@ -50,7 +50,7 @@ bool zlib::isAvailable()
 #endif
 }
 
-ByteVector zlib::decompress(const ByteVector &data)
+ByteVector zlib::decompress([[maybe_unused]] const ByteVector &data)
 {
 #ifdef HAVE_ZLIB
 
diff --git a/taglib/xm/xmproperties.h b/taglib/xm/xmproperties.h
index 1c7e0f60..901a2422 100644
--- a/taglib/xm/xmproperties.h
+++ b/taglib/xm/xmproperties.h
@@ -33,7 +33,6 @@
 namespace TagLib {
   namespace XM {
     class TAGLIB_EXPORT Properties : public AudioProperties {
-      friend class File;
     public:
       /*! Flag bits. */
       enum {