diff --git a/Dockerfile b/Dockerfile
index f17427f..13394e5 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,7 +2,8 @@ FROM focs.ji.sjtu.edu.cn:5000/gitea/runner-images:ubuntu-latest-slim
 
 ENV TZ="Asia/Shanghai"
 
-RUN apt-get update && \
+RUN sed -i s@/deb.debian.org/@/mirrors.tuna.tsinghua.edu.cn/@g /etc/apt/sources.list && \
+    apt-get update && \
     apt-get install -y --no-install-recommends sudo python3-minimal python3-pip git openssh-client && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/* && \