diff --git a/serving/samples/helloworld-go/Dockerfile b/serving/samples/helloworld-go/Dockerfile
index 6e91928c3..fd2e2fa61 100644
--- a/serving/samples/helloworld-go/Dockerfile
+++ b/serving/samples/helloworld-go/Dockerfile
@@ -1,7 +1,7 @@
 # Use the offical Golang image to create a build artifact.
 # This is based on Debian and sets the GOPATH to /go.
 # https://hub.docker.com/_/golang
-FROM golang as builder
+FROM golang:1.12 as builder
 
 # Copy local code to the container image.
 WORKDIR /go/src/github.com/knative/docs/helloworld