diff --git a/testbox/scripts/auto-pull-restart.sh b/testbox/scripts/auto-pull-restart.sh
index 5cdaffb..dec845d 100755
--- a/testbox/scripts/auto-pull-restart.sh
+++ b/testbox/scripts/auto-pull-restart.sh
@@ -240,9 +240,11 @@ run_once() {
   local java_before java_after
   local services_line
 
+  exec 9>&- 2>/dev/null || true
   exec 9>"$LOCK_FILE"
   if ! flock -n 9; then
     log "deploy lock busy; skip this tick"
+    exec 9>&-
     return 0
   fi
 
@@ -301,6 +303,9 @@ run_once() {
     rc=$?
     [ "$rc" -eq 10 ] || log "admin update skipped due to error rc=$rc"
   fi
+
+  flock -u 9
+  exec 9>&-
 }
 
 usage() {