diff --git a/Dockerfile b/Dockerfile
index 9df5d758f0a6c936d8333a0ae8aa635f3958ca94..86807a5c73a49de5ffbdbc9f9a8845164465a489 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM node:8.11.0-alpine@null
+FROM node:8.11.0-alpine@sha256:8af2ad09cdf0cc443ce076971e0c5b593c0fc7250d1fca3afe67fc7a8ff08a21
 
 LABEL maintainer="Rhys Arkins <rhys@arkins.net>"
 LABEL name="renovate"