diff --git a/scripts/lib/upgrade-zulip-stage-2 b/scripts/lib/upgrade-zulip-stage-2
index 26877ebcfe..23747f350f 100755
--- a/scripts/lib/upgrade-zulip-stage-2
+++ b/scripts/lib/upgrade-zulip-stage-2
@@ -351,9 +351,9 @@ if IS_SERVER_UP or not args.skip_puppet:
         restart_args.append("--skip-tornado")
     if args.less_graceful:
         restart_args.append("--less-graceful")
-    subprocess.check_output(["./scripts/restart-server", *restart_args], preexec_fn=su_to_zulip)
+    subprocess.check_call(["./scripts/restart-server", *restart_args], preexec_fn=su_to_zulip)
 else:
-    subprocess.check_output(["./scripts/start-server", "--fill-cache"], preexec_fn=su_to_zulip)
+    subprocess.check_call(["./scripts/start-server", "--fill-cache"], preexec_fn=su_to_zulip)
 
 logging.info("Upgrade complete!")