diff --git a/Makefile b/Makefile
index fac153a..4d92ba8 100644
--- a/Makefile
+++ b/Makefile
@@ -11,4 +11,7 @@ help: always ## Ayuda
 	touch build/$@/$(v)
 	git add build/$@/$(v)
 
+missing:
+	@comm -23 <(find build/ -type f | grep -v /.keep | cut -d / -f 2- | sort) <(find built/ -type f | grep -v /.keep | cut -d / -f 3- | sort)
+
 .PHONY: always