diff --git a/Dockerfile b/Dockerfile
index ae5fa8d..ccb6240 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM docker:27.5.1-dind
+FROM docker:27.5.1-dind@sha256:aa3df78ecf320f5fafdce71c659f1629e96e9de0968305fe1de670e0ca9176ce
 
 # renovate: datasource=pypi depName=determine-docker-tags versioning=semver
 ENV DETERMINE_DOCKER_TAGS_VERSION 0.2.6