diff --git a/.gitea/workflows/build.yaml b/.gitea/workflows/build.yaml
index 0318552..d415e9e 100644
--- a/.gitea/workflows/build.yaml
+++ b/.gitea/workflows/build.yaml
@@ -59,7 +59,7 @@ jobs:
           echo REPO_NAME=$(echo ${GITHUB_REPOSITORY} | awk -F"/" '{print $2}') >> $GITHUB_OUTPUT
       - name: Extract branch name
         shell: bash
-        run: echo "REPO_BRANCH=${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}" >> $GITHUB_OUTPUT
+        run: echo "REPO_BRANCH=${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}" | tr -cd '[:alnum:]_-' >> $GITHUB_OUTPUT
         id: extract_branch
       - name: Build and push Docker image
         uses: https://github.com/docker/build-push-action@v6
@@ -83,4 +83,3 @@ jobs:
             Job: ${{ github.action }}
             Status: ${{ job.status }}
             Source: ${{ github.head_ref }}
-