diff --git a/lumps/Makefile b/lumps/Makefile
index 68854e00..ffbee737 100644
--- a/lumps/Makefile
+++ b/lumps/Makefile
@@ -17,3 +17,5 @@ force:
 
 clean:
 	make -C cph/misc-lumps clean
+	make -C genmidi clean
+
diff --git a/lumps/genmidi/Makefile b/lumps/genmidi/Makefile
index 6ba49756..33c0f750 100644
--- a/lumps/genmidi/Makefile
+++ b/lumps/genmidi/Makefile
@@ -1,4 +1,7 @@
 
-genmidi.lmp:
+genmidi.lmp: config.py instruments/*
 	./mkgenmidi $@
 
+clean:
+	rm -f genmidi.lmp
+