diff --git a/.github/workflows/mxe-dockerimage-stage2.yml b/.github/workflows/mxe-dockerimage-stage2.yml
index 5e56f68cd..de286703c 100644
--- a/.github/workflows/mxe-dockerimage-stage2.yml
+++ b/.github/workflows/mxe-dockerimage-stage2.yml
@@ -21,10 +21,10 @@ jobs:
       run: |
         v=${{ github.event.action }}
         s=".stage1"
-        b=${{ github.event.client_payload.target_branc }} # -BRANCH suffix, unless the branch is master
+        b=${{ github.event.client_payload.target_branch }} # -BRANCH suffix, unless the branch is master
         b=${b/refs\/heads\//}
         b=${b,,} # the name needs to be all lower case
-        if [ $b = "master" ] ; then b="" ; else b="-$b" ; fi
+        if [ "$b" = "master" ] || [ "$b" = "" ] ; then b="" ; else b="-$b" ; fi
         echo "::set-env name=VERSION::${v}${s}"
         echo "::set-env name=NAME::subsurface/mxe-build-container${b}:${v}"