diff --git a/build/mk/cloud/common.mk b/build/mk/cloud/common.mk
index 9a37b9b6dcf8b281716d73f30d46593c1c62227e..73fdd5b9f1256eb7899be2b0fc0d44b90901429d 100755
--- a/build/mk/cloud/common.mk
+++ b/build/mk/cloud/common.mk
@@ -6,7 +6,7 @@ LIBC=$(iTrustee_SDK_PATH)/thirdparty/open_source/musl
 LIBSECURE=$(iTrustee_SDK_PATH)/thirdparty/open_source/libboundscheck/
 
 # set compile parameters
-CFLAGS := -O -W -Wall
+CFLAGS += -O -W -Wall
 CFLAGS += -Werror
 CFLAGS += -fno-short-enums
 CFLAGS += -fno-omit-frame-pointer