diff --git a/src/audio.cc b/src/audio.cc
index 4c80182..ee71201 100644
--- a/src/audio.cc
+++ b/src/audio.cc
@@ -58,7 +58,7 @@ static int audioSoundDecoderReadHandler(void* data, void* buffer, unsigned int s
 
 // AudioOpen
 // 0x41A2EC
-int audioOpen(const char* fname, int flags, ...)
+int audioOpen(const char* fname, int flags)
 {
     char path[80];
     snprintf(path, sizeof(path), "%s", fname);
diff --git a/src/audio.h b/src/audio.h
index f916b16..2b96ac9 100644
--- a/src/audio.h
+++ b/src/audio.h
@@ -5,7 +5,7 @@ namespace fallout {
 
 typedef bool(AudioQueryCompressedFunc)(char* filePath);
 
-int audioOpen(const char* fname, int mode, ...);
+int audioOpen(const char* fname, int mode);
 int audioClose(int handle);
 int audioRead(int handle, void* buffer, unsigned int size);
 long audioSeek(int handle, long offset, int origin);
diff --git a/src/audio_file.cc b/src/audio_file.cc
index 30db375..d1dce84 100644
--- a/src/audio_file.cc
+++ b/src/audio_file.cc
@@ -57,7 +57,7 @@ static int audioFileSoundDecoderReadHandler(void* data, void* buffer, unsigned i
 }
 
 // 0x41A88C
-int audioFileOpen(const char* fname, int flags, ...)
+int audioFileOpen(const char* fname, int flags)
 {
     char path[COMPAT_MAX_PATH];
     strcpy(path, fname);
diff --git a/src/audio_file.h b/src/audio_file.h
index 38c7a02..f00734b 100644
--- a/src/audio_file.h
+++ b/src/audio_file.h
@@ -5,7 +5,7 @@ namespace fallout {
 
 typedef bool(AudioFileQueryCompressedFunc)(char* filePath);
 
-int audioFileOpen(const char* fname, int flags, ...);
+int audioFileOpen(const char* fname, int flags);
 int audioFileClose(int handle);
 int audioFileRead(int handle, void* buf, unsigned int size);
 long audioFileSeek(int handle, long offset, int origin);
diff --git a/src/game_sound.cc b/src/game_sound.cc
index 3423f72..e7a838c 100644
--- a/src/game_sound.cc
+++ b/src/game_sound.cc
@@ -157,7 +157,7 @@ static int _gsound_speech_volume_get_set(int volume);
 static void speechPause();
 static void speechResume();
 static void _gsound_bkg_proc();
-static int gameSoundFileOpen(const char* fname, int access, ...);
+static int gameSoundFileOpen(const char* fname, int access);
 static long _gsound_write_();
 static long gameSoundFileTellNotImplemented(int handle);
 static int gameSoundFileWrite(int handle, const void* buf, unsigned int size);
@@ -898,7 +898,7 @@ int speechLoad(const char* fname, int a2, int a3, int a4)
         return -1;
     }
 
-    if (soundSetFileIO(gSpeechSound, &audioOpen, &audioClose, &audioRead, NULL, &audioSeek, &gameSoundFileTellNotImplemented, &audioGetSize)) {
+    if (soundSetFileIO(gSpeechSound, audioOpen, audioClose, audioRead, NULL, audioSeek, gameSoundFileTellNotImplemented, audioGetSize)) {
         if (gGameSoundDebugEnabled) {
             debugPrint("failed because file IO could not be set for compression.\n");
         }
@@ -1548,7 +1548,7 @@ void _gsound_bkg_proc()
 }
 
 // 0x451A08
-int gameSoundFileOpen(const char* fname, int flags, ...)
+int gameSoundFileOpen(const char* fname, int flags)
 {
     if ((flags & 2) != 0) {
         return -1;
diff --git a/src/platform_compat.cc b/src/platform_compat.cc
index ba49610..339739c 100644
--- a/src/platform_compat.cc
+++ b/src/platform_compat.cc
@@ -187,21 +187,6 @@ void compat_makepath(char* path, const char* drive, const char* dir, const char*
 #endif
 }
 
-int compat_read(int fileHandle, void* buf, unsigned int size)
-{
-    return read(fileHandle, buf, size);
-}
-
-int compat_write(int fileHandle, const void* buf, unsigned int size)
-{
-    return write(fileHandle, buf, size);
-}
-
-long compat_lseek(int fileHandle, long offset, int origin)
-{
-    return lseek(fileHandle, offset, origin);
-}
-
 long compat_tell(int fd)
 {
     return lseek(fd, 0, SEEK_CUR);
diff --git a/src/platform_compat.h b/src/platform_compat.h
index 4da0706..be88974 100644
--- a/src/platform_compat.h
+++ b/src/platform_compat.h
@@ -29,9 +29,6 @@ char* compat_strlwr(char* string);
 char* compat_itoa(int value, char* buffer, int radix);
 void compat_splitpath(const char* path, char* drive, char* dir, char* fname, char* ext);
 void compat_makepath(char* path, const char* drive, const char* dir, const char* fname, const char* ext);
-int compat_read(int fileHandle, void* buf, unsigned int size);
-int compat_write(int fileHandle, const void* buf, unsigned int size);
-long compat_lseek(int fileHandle, long offset, int origin);
 long compat_tell(int fileHandle);
 long compat_filelength(int fd);
 int compat_mkdir(const char* path);
diff --git a/src/sound.cc b/src/sound.cc
index 3881a68..353b605 100644
--- a/src/sound.cc
+++ b/src/sound.cc
@@ -45,6 +45,13 @@ typedef struct FadeSound {
 static void* soundMallocProcDefaultImpl(size_t size);
 static void* soundReallocProcDefaultImpl(void* ptr, size_t size);
 static void soundFreeProcDefaultImpl(void* ptr);
+static long soundFileSize(int fileHandle);
+static long soundTellData(int fileHandle);
+static int soundWriteData(int fileHandle, const void* buf, unsigned int size);
+static int soundReadData(int fileHandle, void* buf, unsigned int size);
+static int soundOpenData(const char* filePath, int flags);
+static long soundSeekData(int fileHandle, long offset, int origin);
+static int soundCloseData(int fileHandle);
 static char* soundFileManglerDefaultImpl(char* fname);
 static void _refreshSoundBuffers(Sound* sound);
 static int _preloadBuffers(Sound* sound);
@@ -77,13 +84,13 @@ static FreeProc* gSoundFreeProc = soundFreeProcDefaultImpl;
 
 // 0x51D494
 static SoundFileIO gSoundDefaultFileIO = {
-    open,
-    close,
-    compat_read,
-    compat_write,
-    compat_lseek,
-    compat_tell,
-    compat_filelength,
+    soundOpenData,
+    soundCloseData,
+    soundReadData,
+    soundWriteData,
+    soundSeekData,
+    soundTellData,
+    soundFileSize,
     -1,
 };
 
@@ -184,6 +191,55 @@ void soundSetMemoryProcs(MallocProc* mallocProc, ReallocProc* reallocProc, FreeP
     gSoundFreeProc = freeProc;
 }
 
+// 0x4AC71C
+static long soundFileSize(int fileHandle)
+{
+    long pos;
+    long size;
+
+    pos = compat_tell(fileHandle);
+    size = lseek(fileHandle, 0, SEEK_END);
+    lseek(fileHandle, pos, SEEK_SET);
+
+    return size;
+}
+
+// 0x4AC750
+static long soundTellData(int fileHandle)
+{
+    return compat_tell(fileHandle);
+}
+
+// 0x4AC758
+static int soundWriteData(int fileHandle, const void* buf, unsigned int size)
+{
+    return write(fileHandle, buf, size);
+}
+
+// 0x4AC760
+static int soundReadData(int fileHandle, void* buf, unsigned int size)
+{
+    return read(fileHandle, buf, size);
+}
+
+// 0x4AC768
+static int soundOpenData(const char* filePath, int flags)
+{
+    return open(filePath, flags);
+}
+
+// 0x4AC774
+static long soundSeekData(int fileHandle, long offset, int origin)
+{
+    return lseek(fileHandle, offset, origin);
+}
+
+// 0x4AC77C
+static int soundCloseData(int fileHandle)
+{
+    return close(fileHandle);
+}
+
 // 0x4AC78C
 char* soundFileManglerDefaultImpl(char* fname)
 {
diff --git a/src/sound.h b/src/sound.h
index 57d371c..ab81e63 100644
--- a/src/sound.h
+++ b/src/sound.h
@@ -46,7 +46,7 @@ typedef enum SoundError {
     SOUND_ERR_COUNT,
 } SoundError;
 
-typedef int SoundOpenProc(const char* filePath, int flags, ...);
+typedef int SoundOpenProc(const char* filePath, int flags);
 typedef int SoundCloseProc(int fileHandle);
 typedef int SoundReadProc(int fileHandle, void* buf, unsigned int size);
 typedef int SoundWriteProc(int fileHandle, const void* buf, unsigned int size);
diff --git a/src/sound_effects_cache.cc b/src/sound_effects_cache.cc
index d11603f..26aead6 100644
--- a/src/sound_effects_cache.cc
+++ b/src/sound_effects_cache.cc
@@ -154,7 +154,7 @@ void soundEffectsCacheFlush()
 
 // sfxc_cached_open
 // 0x4A915C
-int soundEffectsCacheFileOpen(const char* fname, int mode, ...)
+int soundEffectsCacheFileOpen(const char* fname, int mode)
 {
     if (_sfxc_files_open >= SOUND_EFFECTS_MAX_COUNT) {
         return -1;
diff --git a/src/sound_effects_cache.h b/src/sound_effects_cache.h
index 3650bcd..e6e0972 100644
--- a/src/sound_effects_cache.h
+++ b/src/sound_effects_cache.h
@@ -11,7 +11,7 @@ int soundEffectsCacheInit(int cache_size, const char* effectsPath);
 void soundEffectsCacheExit();
 int soundEffectsCacheInitialized();
 void soundEffectsCacheFlush();
-int soundEffectsCacheFileOpen(const char* fname, int mode, ...);
+int soundEffectsCacheFileOpen(const char* fname, int mode);
 int soundEffectsCacheFileClose(int handle);
 int soundEffectsCacheFileRead(int handle, void* buf, unsigned int size);
 int soundEffectsCacheFileWrite(int handle, const void* buf, unsigned int size);