diff --git a/mp3lib/Makefile b/mp3lib/Makefile
index 75bcb8f196..578f3ebda6 100644
--- a/mp3lib/Makefile
+++ b/mp3lib/Makefile
@@ -3,11 +3,11 @@ include ../config.mak
 LIBNAME_COMMON = libmp3.a
 
 SRCS_COMMON = sr1.c
-SRCS_COMMON-$(HAVE_MMX)       += decode_MMX.c
+SRCS_COMMON-$(HAVE_MMX)       += decode_mmx.c
 SRCS_COMMON-$(HAVE_SSE)       += dct64_sse.c
 ifeq ($(ARCH_X86_32),yes)
 SRCS_COMMON                   += decode_i586.c
-SRCS_COMMON-$(HAVE_MMX)       += dct64_MMX.c
+SRCS_COMMON-$(HAVE_MMX)       += dct64_mmx.c
 SRCS_COMMON-$(HAVE_3DNOW)     += dct36_3dnow.c dct64_3dnow.c
 SRCS_COMMON-$(HAVE_3DNOWEX)   += dct36_k7.c dct64_k7.c
 endif
diff --git a/mp3lib/dct64_MMX.c b/mp3lib/dct64_mmx.c
similarity index 100%
rename from mp3lib/dct64_MMX.c
rename to mp3lib/dct64_mmx.c
diff --git a/mp3lib/dct64_sse.c b/mp3lib/dct64_sse.c
index 9c3873996d..ad835ef14f 100644
--- a/mp3lib/dct64_sse.c
+++ b/mp3lib/dct64_sse.c
@@ -2,7 +2,7 @@
  * Discrete Cosine Tansform (DCT) for SSE
  * Copyright (c) 2006 Zuxy MENG <zuxy.meng@gmail.com>
  * based upon code from mp3lib/dct64.c, mp3lib/dct64_altivec.c
- * and mp3lib/dct64_MMX.c
+ * and mp3lib/dct64_mmx.c
  */
 
 #include <libavutil/mem.h>
diff --git a/mp3lib/decode_MMX.c b/mp3lib/decode_mmx.c
similarity index 100%
rename from mp3lib/decode_MMX.c
rename to mp3lib/decode_mmx.c