diff --git a/engine/common/soundlib/libmpg/format.c b/engine/common/soundlib/libmpg/format.c
index 75e3c204..fb40aa7f 100644
--- a/engine/common/soundlib/libmpg/format.c
+++ b/engine/common/soundlib/libmpg/format.c
@@ -56,20 +56,20 @@ static int good_enc( const int enc )
 	return FALSE;
 }
 
-void mpg123_rates( const long **list, size_t *number )
+static void mpg123_rates( const long **list, size_t *number )
 {
 	if( number != NULL ) *number = sizeof( my_rates ) / sizeof( long );
 	if( list != NULL ) *list = my_rates;
 }
 
 // now that's a bit tricky... One build of the library knows only a subset of the encodings.
-void mpg123_encodings( const int **list, size_t *number )
+static void mpg123_encodings( const int **list, size_t *number )
 {
 	if( number != NULL ) *number = sizeof( good_encodings ) / sizeof( int );
 	if( list != NULL ) *list = good_encodings;
 }
 
-int mpg123_encsize( int encoding )
+static int mpg123_encsize( int encoding )
 {
 	return sizeof( short );
 }
@@ -364,7 +364,7 @@ int mpg123_format( mpg123_handle_t *mh, long rate, int channels, int encodings )
 	return r;
 }
 
-int mpg123_format_support( mpg123_handle_t *mh, long rate, int encoding )
+static int mpg123_format_support( mpg123_handle_t *mh, long rate, int encoding )
 {
 	if( mh == NULL )
 		return 0;
diff --git a/engine/common/soundlib/libmpg/frame.c b/engine/common/soundlib/libmpg/frame.c
index 6344b6d6..7a714993 100644
--- a/engine/common/soundlib/libmpg/frame.c
+++ b/engine/common/soundlib/libmpg/frame.c
@@ -393,7 +393,7 @@ void frame_exit( mpg123_handle_t *fr )
 	bc_cleanup( &fr->rdat.buffer );
 }
 
-int mpg123_framedata( mpg123_handle_t *mh, ulong *header, byte **bodydata, size_t *bodybytes )
+static int mpg123_framedata( mpg123_handle_t *mh, ulong *header, byte **bodydata, size_t *bodybytes )
 {
 	if( mh == NULL )
 		return MPG123_BAD_HANDLE;
@@ -512,7 +512,7 @@ mpg_off_t frame_index_find( mpg123_handle_t *fr, mpg_off_t want_frame, mpg_off_t
 	return gopos;
 }
 
-mpg_off_t frame_ins2outs( mpg123_handle_t *fr, mpg_off_t ins )
+static mpg_off_t frame_ins2outs( mpg123_handle_t *fr, mpg_off_t ins )
 {
 	mpg_off_t	outs = 0;
 
diff --git a/engine/common/soundlib/libmpg/mpg123.c b/engine/common/soundlib/libmpg/mpg123.c
index 03968d48..c5b48c6c 100644
--- a/engine/common/soundlib/libmpg/mpg123.c
+++ b/engine/common/soundlib/libmpg/mpg123.c
@@ -15,6 +15,7 @@ GNU General Public License for more details.
 
 #include "mpg123.h"
 #include "sample.h"
+#include "libmpg.h"
 
 static int	initialized = 0;
 
@@ -83,7 +84,7 @@ mpg123_handle_t *mpg123_parnew( mpg123_parm_t *mp, int *error )
 	return fr;
 }
 
-int mpg123_par( mpg123_parm_t *mp, enum mpg123_parms key, long val )
+static int mpg123_par( mpg123_parm_t *mp, enum mpg123_parms key, long val )
 {
 	int	ret = MPG123_OK;
 
@@ -189,7 +190,7 @@ int mpg123_param( mpg123_handle_t *mh, enum mpg123_parms key, long val )
 	}
 }
 
-int mpg123_close( mpg123_handle_t *mh )
+static int mpg123_close( mpg123_handle_t *mh )
 {
 	if( mh == NULL )
 		return MPG123_BAD_HANDLE;
@@ -263,7 +264,7 @@ int mpg123_replace_reader_handle( mpg123_handle_t *mh, mpg_ssize_t (*fread)( voi
 // a) a new choice of decoder
 // b) a changed native format of the MPEG stream
 // ... calls are only valid after parsing some MPEG frame!
-int decode_update( mpg123_handle_t *mh )
+static int decode_update( mpg123_handle_t *mh )
 {
 	long	native_rate;
 	int	b;
@@ -320,13 +321,13 @@ int decode_update( mpg123_handle_t *mh )
 	return 0;
 }
 
-size_t mpg123_safe_buffer( void )
+static size_t mpg123_safe_buffer( void )
 {
 	// real is the largest possible output
 	return sizeof( float ) * 2 * 1152;
 }
 
-size_t mpg123_outblock( mpg123_handle_t *mh )
+static size_t mpg123_outblock( mpg123_handle_t *mh )
 {
 	// try to be helpful and never return zero output block size.
 	if( mh != NULL && mh->outblock > 0 )
@@ -697,7 +698,7 @@ int mpg123_getformat( mpg123_handle_t *mh, int *rate, int *channels, int *encodi
 	return MPG123_OK;
 }
 
-int mpg123_scan( mpg123_handle_t *mh )
+static int mpg123_scan( mpg123_handle_t *mh )
 {
 	mpg_off_t	track_frames = 0;
 	mpg_off_t	track_samples = 0;
@@ -963,8 +964,10 @@ const char *mpg123_plain_strerror( int errcode )
 	}
 }
 
-const char *get_error( mpg123_handle_t *mh )
+const char *get_error( void *handle )
 {
+	mpg123_handle_t *mh = handle;
+
 	if( !mh ) return mpg123_plain_strerror( MPG123_BAD_HANDLE );
 	return mpg123_plain_strerror( mh->err );
 }
diff --git a/engine/common/soundlib/libmpg/parse.c b/engine/common/soundlib/libmpg/parse.c
index 8ef2db2d..b84d472b 100644
--- a/engine/common/soundlib/libmpg/parse.c
+++ b/engine/common/soundlib/libmpg/parse.c
@@ -68,7 +68,7 @@ void set_pointer( mpg123_handle_t *fr, long backstep )
 	fr->bitindex = 0;
 }
 
-int frame_bitrate( mpg123_handle_t *fr )
+static int frame_bitrate( mpg123_handle_t *fr )
 {
 	return tabsel_123[fr->lsf][fr->lay-1][fr->bitrate_index];
 }
@@ -643,7 +643,7 @@ static int forget_head_shift( mpg123_handle_t *fr, ulong *newheadp, int forget )
 // returns:  0: bad or just unparseable tag
 //           1: good, (possibly) new tag info
 //          <0: reader error (may need more data feed, try again)
-int parse_new_id3( mpg123_handle_t *fr, ulong first4bytes )
+static int parse_new_id3( mpg123_handle_t *fr, ulong first4bytes )
 {
 	byte	buf[6];
 	ulong	length=0;
diff --git a/engine/common/soundlib/libmpg/synth.c b/engine/common/soundlib/libmpg/synth.c
index bf1ca981..7e0960ec 100644
--- a/engine/common/soundlib/libmpg/synth.c
+++ b/engine/common/soundlib/libmpg/synth.c
@@ -25,7 +25,7 @@ GNU General Public License for more details.
 	else { *(samples) = REAL_TO_SHORT( sum ); }
 
 // main synth function, uses the plain dct64
-int synth_1to1( float *bandPtr, int channel, mpg123_handle_t *fr, int final )
+static int synth_1to1( float *bandPtr, int channel, mpg123_handle_t *fr, int final )
 {
 	static const int	step = 2;
 	short		*samples = (short *) (fr->buffer.data + fr->buffer.fill);
@@ -147,7 +147,7 @@ static int synth_stereo( float *bandPtr_l, float *bandPtr_r, mpg123_handle_t *fr
 }
 
 // mono to stereo synth, wrapping over synth_1to1
-int synth_1to1_m2s(float *bandPtr, mpg123_handle_t *fr )
+static int synth_1to1_m2s(float *bandPtr, mpg123_handle_t *fr )
 {
 	byte	*samples = fr->buffer.data;
 	int	i, ret;
@@ -165,7 +165,7 @@ int synth_1to1_m2s(float *bandPtr, mpg123_handle_t *fr )
 }
 
 // mono synth, wrapping over synth_1to1
-int synth_1to1_mono( float *bandPtr, mpg123_handle_t *fr )
+static int synth_1to1_mono( float *bandPtr, mpg123_handle_t *fr )
 {
 	short	samples_tmp[BLOCK];
 	short	*tmp1 = samples_tmp;