diff --git a/Dockerfile b/Dockerfile
index 20ebc80..6490135 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM debian:bullseye-slim
+FROM debian:bullseye-slim@sha256:34b63f55a4b193ad03c5ddb4b3f8546c797763ed708f0df5309ecb9507d15179
 
 RUN adduser --disabled-password --gecos "" --no-create-home --uid 1000 cronos