diff --git a/Makefile b/Makefile
index e1bb370..d20ad8f 100644
--- a/Makefile
+++ b/Makefile
@@ -19,7 +19,7 @@ options:
 
 ${OBJ}: config.h config.mk
 
-config.h:
+config.h: config.def.h
 	@echo creating $@ from config.def.h
 	@cp config.def.h $@