diff --git a/src/win/Makefile.mingw b/src/win/Makefile.mingw
index b20dd86db..040b14aee 100644
--- a/src/win/Makefile.mingw
+++ b/src/win/Makefile.mingw
@@ -511,6 +511,10 @@ ifeq ($(DEV_BRANCH), y)
  endif
 endif
 
+ifeq ($(RTMIDI), y)
+ OPTS += -DUSE_RTMIDI
+endif
+
 
 # Final versions of the toolchain flags.
 CFLAGS := $(OPTS) $(DFLAGS) $(COPTIM) $(AOPTIM) \
@@ -767,7 +771,6 @@ endif
 
 ifeq ($(RTMIDI), y)
  SNDOBJ += midi_rtmidi.o
- OPTS += -DUSE_RTMIDI
 endif
 
 OBJ := $(MAINOBJ) $(CPUOBJ) $(CHIPSETOBJ) $(MCHOBJ) $(DEVOBJ) $(MEMOBJ) \