diff --git a/docker/runner-base/Dockerfile b/docker/runner-base/Dockerfile
index 75297c3..fd5d9b5 100644
--- a/docker/runner-base/Dockerfile
+++ b/docker/runner-base/Dockerfile
@@ -3,7 +3,9 @@
 # 与 src/infra/docker.rs 的 user: "1000:1000"、working_dir: "/code" 对齐。
 FROM alpine:3.18
 
-RUN addgroup -S runner && adduser -S runner -G runner -u 1000 \
+# 替换为国内镜像源，避免 apk 拉取 dl-cdn.alpinelinux.org 失败。
+RUN sed -i 's|dl-cdn.alpinelinux.org|mirrors.tuna.tsinghua.edu.cn|g' /etc/apk/repositories \
+    && addgroup -S runner && adduser -S runner -G runner -u 1000 \
     && mkdir -p /code \
     && chown -R runner:runner /code