diff --git a/Dockerfile b/Dockerfile
index 8d76c5d..f301f65 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM node:9-alpine
+FROM node:9-alpine@sha256:de0fc4272136f43c366f68681743b5717e2e7db7646b20c714005274cd638204
 MAINTAINER "Stefan Walther"
 
 ARG PORT=9696