diff --git a/Dockerfile b/Dockerfile
index 02f3f245..e1834cf3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,4 @@
-ARG BUN_VERSION="1.3.13"
-
-FROM oven/bun:${BUN_VERSION}-alpine AS base
+FROM oven/bun:1.3.13-alpine@sha256:4de475389889577f346c636f956b42a5c31501b654664e9ae5726f94d7bb5349 AS base
 
 ARG RESTIC_VERSION="0.18.1"
 ARG RCLONE_VERSION="1.73.5"