diff --git a/browser_patches/firefox/clean.sh b/browser_patches/firefox/clean.sh
index 89936dd0a1..1c7b9a0581 100755
--- a/browser_patches/firefox/clean.sh
+++ b/browser_patches/firefox/clean.sh
@@ -6,7 +6,7 @@ trap "cd $(pwd -P)" EXIT
 cd "$(dirname $0)"
 cd "checkout"
 
-OBJ_FOLDER=$(ls -1 | grep obj-)
+OBJ_FOLDER=$(ls -1 | grep obj- || true)
 if [[ -d $OBJ_FOLDER ]]; then
   rm -rf $OBJ_FOLDER
 fi