diff --git a/docker-for-mac/Makefile b/docker-for-mac/Makefile
new file mode 100644
index 0000000000..3f9dd5a0dc
--- /dev/null
+++ b/docker-for-mac/Makefile
@@ -0,0 +1,10 @@
+.PHONY:
+check:
+	for img in $$(git ls-files images); do	\
+	  base=$$(basename "$$img");		\
+	  if ! git grep -q -F "$$base"; then	\
+	    echo >&2 "unused image: $$img";	\
+	    pass=false;				\
+	  fi;					\
+	done;					\
+	$$pass