diff --git a/scripts/update-server-fast.sh b/scripts/update-server-fast.sh
index f064ca9..4b9b267 100755
--- a/scripts/update-server-fast.sh
+++ b/scripts/update-server-fast.sh
@@ -2,7 +2,7 @@
 set -euo pipefail
 
 # 快速更新脚本：适合已经完成首次部署后的日常代码更新。
-# 只做 git 更新、前端 build、重启用户级服务；不检查/安装系统依赖。
+# 只做 git 更新、前端 build、重启 systemd 服务；不检查/安装系统依赖。
 # 如果 pyproject.toml 在本次更新中变化，会额外同步一次 Python 依赖。
 # 如果本次改动包含依赖、systemd 模板或部署脚本变化，请使用 scripts/deploy-ubuntu.sh。
 
@@ -73,6 +73,18 @@ sync_python_dependencies_if_needed() {
 	"${python_bin}" -m pip install -e .
 }
 
+systemctl_for_scope() {
+	if [[ "${SERVICE_SCOPE}" == "system" ]]; then
+		if [[ "${EUID}" == "0" ]]; then
+			systemctl "$@"
+		else
+			sudo systemctl "$@"
+		fi
+	else
+		systemctl --user "$@"
+	fi
+}
+
 cd "${ROOT_DIR}"
 [[ -d .git ]] || fail "${ROOT_DIR} 不是 git 仓库。"
 
@@ -111,19 +123,11 @@ export PATH="$(dirname "${npm_bin}"):${PATH}"
 "${npm_bin}" run build
 
 log "重启 ${SERVICE_SCOPE} 服务"
-if [[ "${SERVICE_SCOPE}" == "system" ]]; then
-	systemctl restart "${BACKEND_SERVICE}" "${FRONTEND_SERVICE}"
-else
-	systemctl --user restart "${BACKEND_SERVICE}" "${FRONTEND_SERVICE}"
-fi
+systemctl_for_scope restart "${BACKEND_SERVICE}" "${FRONTEND_SERVICE}"
 
 log "健康检查"
 sleep 1
-if [[ "${SERVICE_SCOPE}" == "system" ]]; then
-	systemctl --no-pager --lines=0 status "${BACKEND_SERVICE}" "${FRONTEND_SERVICE}"
-else
-	systemctl --user --no-pager --lines=0 status "${BACKEND_SERVICE}" "${FRONTEND_SERVICE}"
-fi
+systemctl_for_scope --no-pager --lines=0 status "${BACKEND_SERVICE}" "${FRONTEND_SERVICE}"
 
 echo
 echo "快速更新完成。"