diff --git a/Dockerfile-linux b/Dockerfile-linux
index 72373d5..0be9edf 100644
--- a/Dockerfile-linux
+++ b/Dockerfile-linux
@@ -1,4 +1,4 @@
-FROM ubuntu:jammy
+FROM ubuntu:jammy@sha256:f9d633ff6640178c2d0525017174a688e2c1aef28f0a0130b26bd5554491f0da
 
 ARG zlib_version
 ARG zlib_hash
diff --git a/Dockerfile-linux-arm64 b/Dockerfile-linux-arm64
index 9ea8df3..4d1a2a8 100644
--- a/Dockerfile-linux-arm64
+++ b/Dockerfile-linux-arm64
@@ -1,4 +1,4 @@
-FROM ubuntu:jammy
+FROM ubuntu:jammy@sha256:f9d633ff6640178c2d0525017174a688e2c1aef28f0a0130b26bd5554491f0da
 
 ARG zlib_version
 ARG zlib_hash
diff --git a/Dockerfile-mingw b/Dockerfile-mingw
index 11cec1d..065f8db 100644
--- a/Dockerfile-mingw
+++ b/Dockerfile-mingw
@@ -1,4 +1,4 @@
-FROM ubuntu:jammy
+FROM ubuntu:jammy@sha256:f9d633ff6640178c2d0525017174a688e2c1aef28f0a0130b26bd5554491f0da
 
 ARG zlib_version
 ARG zlib_hash