diff --git a/Makefile.inc b/Makefile.inc
index 18115e5c020..b15b90a115e 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -60,7 +60,9 @@ else
   S = -s
 endif
 
-zephyrmake	= @+$(MAKE) -C $(ZEPHYR_BASE)  O=$(1) CFLAGS=$(CFLAGS) \
+export CFLAGS
+
+zephyrmake	= @+$(MAKE) -C $(ZEPHYR_BASE)  O=$(1) \
 			PROJECT=$(PROJECT_BASE) SOURCE_DIR=$(SOURCE_DIR) $(2)
 
 BOARDCONFIG = $(O)/.board_$(BOARD)