--- a/media/libaom/generate_sources_mozbuild.sh
+++ b/media/libaom/generate_sources_mozbuild.sh
@@ -163,18 +163,18 @@ function gen_config_files {
   ./configure $2 #> /dev/null
 
   # Disable HAVE_UNISTD_H.
   ( echo '/HAVE_UNISTD_H'; echo 'd' ; echo 'w' ; echo 'q' ) | ed -s aom_config.h
 
   local ASM_CONV=ads2gas.pl
 
   # Generate aom_config.asm.
-  if [[ "$1" == *x64* ]] || [[ "$1" == *ia32* ]]; then
-    egrep "#define [A-Z0-9_]+ [01]" aom_config.h | awk '{print "%define " $2 " " $3}' > aom_config.asm
+  if [[ "$1" == *x64* ]] || [[ "$1" == *ia32* ]] || [[ "$1" == *mingw* ]]; then
+    egrep "#define [A-Z0-9_]+ [01]" aom_config.h | awk '{print $2 " equ " $3}' > aom_config.asm
   else
     egrep "#define [A-Z0-9_]+ [01]" aom_config.h | awk '{print $2 " EQU " $3}' | perl $BASE_DIR/$LIBAOM_SRC_DIR/build/make/$ASM_CONV > aom_config.asm
   fi
 
   mkdir -p $BASE_DIR/$LIBAOM_CONFIG_DIR/$1
   cp aom_config.* $BASE_DIR/$LIBAOM_CONFIG_DIR/$1
   make_clean
   rm -rf aom_config.*