diff --git a/Makefile b/Makefile
index 74ebdbf..3277990 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,8 @@ ifeq ($(ARCH),$(filter $(ARCH),i386 i686))
 endif
 
 LIBDIR := /lib
-CFLAGS = -ggdb3 -O2 -Wall -Iarch/${ARCH} -Iarch/common
+CFLAGS := -ggdb3 -O2 -Wall
+CPPFLAGS := -Iarch/${ARCH} -Iarch/common
 
 LIBUCONTEXT_C_SRC = $(wildcard arch/${ARCH}/*.c)
 LIBUCONTEXT_S_SRC = $(wildcard arch/${ARCH}/*.S)