diff --git a/Dockerfile b/Dockerfile
index 4c0e1d3..1c41c86 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM node:10.24.1-buster as build
+FROM node:10.24.1-buster@sha256:05e259ab6478ae6032163ce34683bfccb495c8219f2f01a8d30889bb3ce33084 as build
 
 # renovate: datasource=github-tags depName=gchq/CyberChef versioning=semver
 ENV CYBERCHEF_VERSION v9.28.0