diff --git a/Makefile b/Makefile
index 2d00feb..d8027e7 100644
--- a/Makefile
+++ b/Makefile
@@ -26,7 +26,7 @@ valgrind: clean test
 
 -include $(DEPS)
 
-obj/%.o: src/%.c
+obj/%.o: src/%.c obj
 	$(CC) $(CFLAGS) -MMD -c -o $@ $<
 
 obj: