diff --git a/taglib/audioproperties.h b/taglib/audioproperties.h
index a2df2f46..d0684d17 100644
--- a/taglib/audioproperties.h
+++ b/taglib/audioproperties.h
@@ -26,6 +26,7 @@
 #ifndef TAGLIB_AUDIOPROPERTIES_H
 #define TAGLIB_AUDIOPROPERTIES_H
 
+#include "taglib.h"
 #include "taglib_export.h"
 
 #include <memory>
@@ -77,6 +78,7 @@ namespace TagLib {
       *
       * \deprecated Use lengthInSeconds().
       */
+    TAGLIB_DEPRECATED
     virtual int length() const;
 
     /*!
diff --git a/taglib/mpeg/id3v2/id3v2.h b/taglib/mpeg/id3v2/id3v2.h
index 36e76429..6dfba5fb 100644
--- a/taglib/mpeg/id3v2/id3v2.h
+++ b/taglib/mpeg/id3v2/id3v2.h
@@ -15,8 +15,8 @@ namespace TagLib {
      * Used to specify which version of the ID3 standard to use when saving tags.
      */
     enum Version {
-      v3 = 3, //<! ID3v2.3
-      v4 = 4  //<! ID3v2.4
+      v3 = 3, //!< ID3v2.3
+      v4 = 4  //!< ID3v2.4
     };
   } // namespace ID3v2
 }  // namespace TagLib
diff --git a/taglib/mpeg/id3v2/id3v2framefactory.h b/taglib/mpeg/id3v2/id3v2framefactory.h
index 733ad533..39db8c4e 100644
--- a/taglib/mpeg/id3v2/id3v2framefactory.h
+++ b/taglib/mpeg/id3v2/id3v2framefactory.h
@@ -135,8 +135,6 @@ namespace TagLib {
        *
        * \param data data of the frame (might be modified)
        * \param tagHeader the tag header
-       * \param header reference to frame header pointer, will be set to
-       *               nullptr if the frame is invalid
        * \return {header, ok}: header is a created frame header or nullptr
        *         if the frame is invalid; ok is true if the frame is supported.
        */
diff --git a/taglib/toolkit/taglib.h b/taglib/toolkit/taglib.h
index d23c25d4..3cbf8ea6 100644
--- a/taglib/toolkit/taglib.h
+++ b/taglib/toolkit/taglib.h
@@ -38,15 +38,7 @@
 #define TAGLIB_CONSTRUCT_BITSET(x) static_cast<unsigned long>(x)
 #endif
 
-#if __cplusplus >= 201402
 #define TAGLIB_DEPRECATED [[deprecated]]
-#elif defined(__GNUC__) || defined(__clang__)
-#define TAGLIB_DEPRECATED __attribute__((deprecated))
-#elif defined(_MSC_VER)
-#define TAGLIB_DEPRECATED __declspec(deprecated)
-#else
-#define TAGLIB_DEPRECATED
-#endif
 
 #ifndef _WIN32
 #include <sys/types.h>
diff --git a/taglib/toolkit/tfile.h b/taglib/toolkit/tfile.h
index d0945998..2fb1d5ca 100644
--- a/taglib/toolkit/tfile.h
+++ b/taglib/toolkit/tfile.h
@@ -66,8 +66,8 @@ namespace TagLib {
      * Specify which tags to strip either explicitly, or on save.
      */
     enum StripTags {
-      StripNone,  //<! Don't strip any tags
-      StripOthers //<! Strip all tags not explicitly referenced in method call
+      StripNone,  //!< Don't strip any tags
+      StripOthers //!< Strip all tags not explicitly referenced in method call
     };
 
     /*!
@@ -75,8 +75,8 @@ namespace TagLib {
      * types should be synchronized.
      */
     enum DuplicateTags {
-      Duplicate,     //<! Synchronize values between different tag types
-      DoNotDuplicate //<! Do not synchronize values between different tag types
+      Duplicate,     //!< Synchronize values between different tag types
+      DoNotDuplicate //!< Do not synchronize values between different tag types
     };
 
     /*!
diff --git a/tests/test_it.cpp b/tests/test_it.cpp
index 1dff71be..d4bba70e 100644
--- a/tests/test_it.cpp
+++ b/tests/test_it.cpp
@@ -107,7 +107,7 @@ private:
     CPPUNIT_ASSERT(nullptr != p);
     CPPUNIT_ASSERT(nullptr != t);
 
-    CPPUNIT_ASSERT_EQUAL( 0, p->length());
+    CPPUNIT_ASSERT_EQUAL( 0, p->lengthInSeconds());
     CPPUNIT_ASSERT_EQUAL( 0, p->bitrate());
     CPPUNIT_ASSERT_EQUAL( 0, p->sampleRate());
     CPPUNIT_ASSERT_EQUAL(64, p->channels());
diff --git a/tests/test_mod.cpp b/tests/test_mod.cpp
index 2986c7d1..2e20b391 100644
--- a/tests/test_mod.cpp
+++ b/tests/test_mod.cpp
@@ -113,7 +113,7 @@ private:
     CPPUNIT_ASSERT(nullptr != p);
     CPPUNIT_ASSERT(nullptr != t);
 
-    CPPUNIT_ASSERT_EQUAL(0, p->length());
+    CPPUNIT_ASSERT_EQUAL(0, p->lengthInSeconds());
     CPPUNIT_ASSERT_EQUAL(0, p->bitrate());
     CPPUNIT_ASSERT_EQUAL(0, p->sampleRate());
     CPPUNIT_ASSERT_EQUAL(8, p->channels());
diff --git a/tests/test_s3m.cpp b/tests/test_s3m.cpp
index 0438ecf8..0a225520 100644
--- a/tests/test_s3m.cpp
+++ b/tests/test_s3m.cpp
@@ -98,7 +98,7 @@ private:
     CPPUNIT_ASSERT(nullptr != p);
     CPPUNIT_ASSERT(nullptr != t);
 
-    CPPUNIT_ASSERT_EQUAL( 0, p->length());
+    CPPUNIT_ASSERT_EQUAL( 0, p->lengthInSeconds());
     CPPUNIT_ASSERT_EQUAL( 0, p->bitrate());
     CPPUNIT_ASSERT_EQUAL( 0, p->sampleRate());
     CPPUNIT_ASSERT_EQUAL(16, p->channels());
diff --git a/tests/test_xm.cpp b/tests/test_xm.cpp
index 33a74b71..76b88837 100644
--- a/tests/test_xm.cpp
+++ b/tests/test_xm.cpp
@@ -130,7 +130,7 @@ public:
     CPPUNIT_ASSERT(nullptr != p);
     CPPUNIT_ASSERT(nullptr != t);
 
-    CPPUNIT_ASSERT_EQUAL(0, p->length());
+    CPPUNIT_ASSERT_EQUAL(0, p->lengthInSeconds());
     CPPUNIT_ASSERT_EQUAL(0, p->bitrate());
     CPPUNIT_ASSERT_EQUAL(0, p->sampleRate());
     CPPUNIT_ASSERT_EQUAL(8, p->channels());
@@ -176,7 +176,7 @@ private:
     CPPUNIT_ASSERT(nullptr != p);
     CPPUNIT_ASSERT(nullptr != t);
 
-    CPPUNIT_ASSERT_EQUAL(0, p->length());
+    CPPUNIT_ASSERT_EQUAL(0, p->lengthInSeconds());
     CPPUNIT_ASSERT_EQUAL(0, p->bitrate());
     CPPUNIT_ASSERT_EQUAL(0, p->sampleRate());
     CPPUNIT_ASSERT_EQUAL(8, p->channels());