diff --git a/docker/alpine/Dockerfile b/docker/alpine/Dockerfile
index f8346152..df884485 100644
--- a/docker/alpine/Dockerfile
+++ b/docker/alpine/Dockerfile
@@ -56,6 +56,4 @@ CMD ss-server -s $SERVER_ADDR \
               --fast-open \
               -d $DNS_ADDR \
               -d $DNS_ADDR_2 \
-              -U \
               -u
-