diff --git a/Makefile b/Makefile
index 747229a..fa5cf9a 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ PREFIX = /usr/local
MANPREFIX = $(PREFIX)/share/man
CC = gcc
-CFLAGS = -std=c99 -Wall -pedantic -O2 -I$(PREFIX)/include -DHAVE_GIFLIB
+CFLAGS += -std=c99 -Wall -pedantic -O2 -I$(PREFIX)/include -DHAVE_GIFLIB
LDFLAGS = -L$(PREFIX)/lib
LIBS = -lX11 -lImlib2 -lgif