diff --git a/libao2/Makefile b/libao2/Makefile
index eaec3216e0..778256d464 100644
--- a/libao2/Makefile
+++ b/libao2/Makefile
@@ -4,7 +4,7 @@ include config.mak
 LIBNAME = libao2.a
 
 # TODO: moveout ao_sdl.c so it's only used when SDL is detected
-SRCS=audio_out.c ao_mpegpes.c ao_null.c ao_pcm.c $(OPTIONAL_SRCS)
+SRCS=afmt.c audio_out.c ao_mpegpes.c ao_null.c ao_pcm.c $(OPTIONAL_SRCS)
 OBJS=$(SRCS:.c=.o)
 
 CFLAGS  = $(OPTFLAGS) -I. -I.. $(SDL_INC) $(EXTRA_INC)
diff --git a/libao2/afmt.c b/libao2/afmt.c
new file mode 100644
index 0000000000..44eb522c19
--- /dev/null
+++ b/libao2/afmt.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "../config.h"
+#include "afmt.h"
+
+char *audio_out_format_name(int format)
+{
+    switch (format)
+    {
+	case AFMT_MU_LAW:
+	    return("Mu-Law");
+	case AFMT_A_LAW:
+	    return("A-Law");
+	case AFMT_IMA_ADPCM:
+	    return("Ima-ADPCM");
+	case AFMT_S8:
+	    return("Signed 8-bit");
+	case AFMT_U8:
+	    return("Unsigned 8-bit");
+	case AFMT_U16_LE:
+	    return("Unsigned 16-bit (Little-Endian)");
+	case AFMT_U16_BE: 
+	    return("Unsigned 16-bit (Big-Endian)");
+	case AFMT_S16_LE:
+	    return("Signed 16-bit (Little-Endian)");
+	case AFMT_S16_BE:
+	    return("Signed 16-bit (Big-Endian)");
+	case AFMT_MPEG:
+	    return("MPEG (2) audio");
+	case AFMT_AC3:
+	    return("AC3");
+/*
+  the following two formats are not available with old linux kernel
+  headers (e.g. in 2.2.16)
+*/
+#ifdef AFMT_S32_LE
+	case AFMT_S32_LE:
+	    return("Signed 32-bit (Little-Endian)");
+#endif
+#ifdef AFMT_S32_BE
+	case AFMT_S32_BE:
+	    return("Signed 32-bit (Big-Endian)");
+#endif
+    }
+    return("Unknown");
+}
diff --git a/libao2/audio_out.c b/libao2/audio_out.c
index 075445488e..0af78067be 100644
--- a/libao2/audio_out.c
+++ b/libao2/audio_out.c
@@ -77,45 +77,3 @@ ao_functions_t* audio_out_drivers[] =
 //	&audio_out_pss,
 	NULL
 };
-
-char *audio_out_format_name(int format)
-{
-    switch (format)
-    {
-	case AFMT_MU_LAW:
-	    return("Mu-Law");
-	case AFMT_A_LAW:
-	    return("A-Law");
-	case AFMT_IMA_ADPCM:
-	    return("Ima-ADPCM");
-	case AFMT_S8:
-	    return("Signed 8-bit");
-	case AFMT_U8:
-	    return("Unsigned 8-bit");
-	case AFMT_U16_LE:
-	    return("Unsigned 16-bit (Little-Endian)");
-	case AFMT_U16_BE: 
-	    return("Unsigned 16-bit (Big-Endian)");
-	case AFMT_S16_LE:
-	    return("Signed 16-bit (Little-Endian)");
-	case AFMT_S16_BE:
-	    return("Signed 16-bit (Big-Endian)");
-	case AFMT_MPEG:
-	    return("MPEG (2) audio");
-	case AFMT_AC3:
-	    return("AC3");
-/*
-  the following two formats are not available with old linux kernel
-  headers (e.g. in 2.2.16)
-*/
-#ifdef AFMT_S32_LE
-	case AFMT_S32_LE:
-	    return("Signed 32-bit (Little-Endian)");
-#endif
-#ifdef AFMT_S32_BE
-	case AFMT_S32_BE:
-	    return("Signed 32-bit (Big-Endian)");
-#endif
-    }
-    return("Unknown");
-}