diff --git a/backup/Dockerfile b/backup/Dockerfile
index 274cba84e3eb9f1276bc754ff3bb2af9f3f763b3..c5d198c459a6fabcb982da807c53862026894d41 100644
--- a/backup/Dockerfile
+++ b/backup/Dockerfile
@@ -1,11 +1,11 @@
-FROM docker.io/library/alpine:3.14
+FROM docker.io/library/alpine:3.21
 # hadolint ignore=DL3018
-RUN echo 'https://dl-cdn.alpinelinux.org/alpine/edge/testing' >> /etc/apk/repositories && \
-    echo 'https://dl-cdn.alpinelinux.org/alpine/edge/community' >> /etc/apk/repositories && \
+RUN echo '@testing https://dl-cdn.alpinelinux.org/alpine/edge/testing' >> /etc/apk/repositories && \
+    echo '@community https://dl-cdn.alpinelinux.org/alpine/v3.21/community' >> /etc/apk/repositories && \
     apk add --update --no-cache \
         findutils \
-        skopeo \
-        reg \
+        skopeo@community \
+        reg@testing \
     ;
 COPY --chown=root:root backup /usr/local/bin/backup
 COPY --chown=root:root restore /usr/local/bin/restore