diff --git a/Makefile b/Makefile
index 1d3265d..5211c5c 100755
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ CC?=gcc
 #CXX=g++
 #CXX=icpc
 
-CFLAGS= $(CFLAGS) $(OPTFLAGS) $(shell sdl-config --cflags) -Imast -Iz80
+CFLAGS:= $(CFLAGS) $(OPTFLAGS) $(shell sdl-config --cflags) -Imast -Iz80
 
 Z80OBJ = z80/z80.o
 MASTOBJ = mast/area.o mast/dpsg.o mast/draw.o mast/emu2413.o mast/frame.o mast/load.o mast/map.o mast/mast.o mast/mem.o mast/samp.o mast/snd.o mast/vgm.o mast/state.o mast/setup.o