diff --git a/images/404-server/Makefile b/images/404-server/Makefile
index e46815c41..89bbcba91 100644
--- a/images/404-server/Makefile
+++ b/images/404-server/Makefile
@@ -20,7 +20,7 @@
 
 all: push
 
-TAG=1.4
+TAG?=1.4
 PREFIX?=gcr.io/google_containers/defaultbackend
 ARCH?=amd64