diff --git a/Dockerfile b/Dockerfile
index a1e122f..5373446 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM alpine:3.20.1 as openssl-builder
+FROM alpine:3.20.1@sha256:b89d9c93e9ed3597455c90a0b88a8bbb5cb7188438f70953fede212a0c4394e0 as openssl-builder
 
 ENV OPENSSL_URL https://www.openssl.org/source/openssl-3.3.1.tar.gz
 ENV OPENSSL_SHA256 777cd596284c883375a2a7a11bf5d2786fc5413255efab20c50d6ffe6d020b7e
@@ -34,7 +34,7 @@
   rm -rf /usr/src/openssl
 
 
-FROM alpine:3.20.1
+FROM alpine:3.20.1@sha256:b89d9c93e9ed3597455c90a0b88a8bbb5cb7188438f70953fede212a0c4394e0
 
 # runtime dependencies
 RUN set -eux; \