diff --git a/src/Makefile b/src/Makefile
index c2c2e40bd..3a453dec4 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -516,7 +516,7 @@ MSG_CLEANING = Cleaning project:
 ifeq ($(PCB), ARM)
   ALL_CPPFLAGS = -c -mcpu=$(MCU) -mthumb -fomit-frame-pointer -fverbose-asm -Wa,-ahlms=open9x.lst -Dat91sam3s4 -DRUN_FROM_FLASH=1 $(CPPFLAGS) $(GENDEPFLAGS)
 else
-  ALL_CPPFLAGS = -mmcu=$(MCU) -I. -x c++ $(CPPFLAGS) $(GENDEPFLAGS) -fwhole-program
+  ALL_CPPFLAGS = -mmcu=$(MCU) -I. -x c++ $(CPPFLAGS) $(GENDEPFLAGS) -fwhole-program -mstrict-X
 endif
 
 MAJ_VER = ${shell sh -c "grep \"MAJ_VERS\" open9x.h | cut -d\  -f3 | egrep -o \"[[:digit:]]\""}