diff --git a/Dockerfile b/Dockerfile
index 1a0b4a5..be022e6 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.12
+FROM alpine:3.12@sha256:074d3636ebda6dd446d0d00304c4454f468237fdacf08fb0eeac90bdbfa1bac7
 
 LABEL maintainer="Robert Kaussow <mail@thegeeklab.de>"
 LABEL org.opencontainers.image.authors="Robert Kaussow <mail@thegeeklab.de>"