diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index e7f0717..e3f8ccf 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -36,7 +36,7 @@ jobs:
         ]
     steps:
       - name: Set lowercase branch name
-        run: echo "BRANCH_NAME=${GITHUB_REF_NAME,,}" >> $GITHUB_ENV
+        run: echo "BRANCH_NAME=$(echo $GITHUB_REF_NAME | tr '[:upper:]' '[:lower:]')" >> $GITHUB_ENV
 
       - name: Echo env
         run: echo ${{ env.BRANCH_NAME }}