diff --git a/Makefile b/Makefile
index 2fa026f..200fb92 100644
--- a/Makefile
+++ b/Makefile
@@ -28,6 +28,8 @@ $(proj)-ns-srcs := \
 
 $(proj)-ns-cflags := -Ilib
 
+$(proj)-cfg-cflags := -Ilib
+
 $(proj)-lookup-srcs := \
 	src/lookup.c \
 	src/util.c \