diff --git a/.github/workflows/build_humble.yaml b/.github/workflows/build_humble.yaml
index 917848d..634707a 100644
--- a/.github/workflows/build_humble.yaml
+++ b/.github/workflows/build_humble.yaml
@@ -36,7 +36,9 @@ jobs:
           required-ros-distributions: humble
       - name: Checkout Aerostack2
         run : |
-          echo "repositories:\n  aerostack2:\n    type: git\n    url: https://github.com/aerostack2/aerostack2.git\n    version:  ${{ github.event.inputs.target_branch }} " >> /tmp/dependencies.repos
+          export TARGET_BRANCH=${{ github.event.inputs.target_branch }} 
+          if [ -z "$TARGET_BRANCH" ]; then export TARGET_BRANCH=main; echo "No target branch provided, using $TARGET_BRANCH";  fi
+          echo "repositories:\n  aerostack2:\n    type: git\n    url: https://github.com/aerostack2/aerostack2.git\n    version:  $TARGET_BRANCH " >> /tmp/dependencies.repos
       - name: build and test
         uses: ros-tooling/action-ros-ci@v0.3
         with: