diff --git a/Makefile b/Makefile
index e9a0784..f3f046f 100644
--- a/Makefile
+++ b/Makefile
@@ -149,7 +149,7 @@
 				-D__ASSEMBLY__ -ffreestanding 			\
 				-Wa,--fatal-warnings
 TF_CFLAGS		+=	$(CPPFLAGS) $(TF_CFLAGS_$(ARCH))		\
-				-ffreestanding -Wall -std=c99 -Os		\
+				-ffreestanding -fno-builtin -Wall -std=c99 -Os	\
 				-ffunction-sections -fdata-sections
 
 LDFLAGS			+=	--fatal-warnings -O1