diff --git a/Makefile b/Makefile
index 523df3a..5d06439 100644
--- a/Makefile
+++ b/Makefile
@@ -6,7 +6,7 @@ all: sxiv
 
 include config.mk
 
-CPPFLAGS += -I. -DVERSION=\"$(VERSION)\" -DHAVE_GIFLIB=$(HAVE_GIFLIB) -DHAVE_LIBEXIF=$(HAVE_LIBEXIF)
+override CPPFLAGS += -I. -DVERSION=\"$(VERSION)\" -DHAVE_GIFLIB=$(HAVE_GIFLIB) -DHAVE_LIBEXIF=$(HAVE_LIBEXIF)
 
 LDLIBS := -lImlib2 -lX11 -lXft