--- a/media/libtheora/lib/Makefile.in
+++ b/media/libtheora/lib/Makefile.in
@@ -44,21 +44,19 @@ include $(DEPTH)/config/autoconf.mk
 MODULE		= theora
 LIBRARY_NAME	= theora
 FORCE_STATIC_LIB= 1
 
 # The encoder is currently not included.
 DEFINES += -DTHEORA_DISABLE_ENCODE
 
 ifeq ($(findstring 86,$(OS_TEST)), 86)
-DEFINES += -DOC_X86ASM
+ifneq ($(OS_ARCH),WINNT)
+DEFINES += -DOC_X86ASM -DUSE_ASM
 endif
-
-ifeq ($(OS_ARCH),Linux)
-DEFINES += -DUSE_ASM
 endif
 
 CSRCS		= \
 		cpu.c \
 		dec/huffdec.c \
 		dec/quant.c \
 		dec/dequant.c \
 		dec/bitwise.c \