diff --git a/Makefile b/Makefile
index 9c0ab72..8a1ff94 100644
--- a/Makefile
+++ b/Makefile
@@ -172,7 +172,7 @@
 ASFLAGS_aarch32		=	$(march32-directive)
 ASFLAGS_aarch64		=	-march=armv8-a
 
-CPPFLAGS		=	${DEFINES} ${INCLUDES} -nostdinc		\
+CPPFLAGS		=	${DEFINES} ${INCLUDES} ${MBEDTLS_INC} -nostdinc		\
 				-Wmissing-include-dirs -Werror
 ASFLAGS			+=	$(CPPFLAGS) $(ASFLAGS_$(ARCH))			\
 				-D__ASSEMBLY__ -ffreestanding 			\