diff --git a/bin/gstack-slug b/bin/gstack-slug
index 24bbca4f1..87d4bb9ba 100755
--- a/bin/gstack-slug
+++ b/bin/gstack-slug
@@ -49,7 +49,7 @@ if [[ -n "$SLUG" ]]; then
 fi
 
 RAW_BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null) || RAW_BRANCH=""
-BRANCH=$(printf '%s' "${RAW_BRANCH:-}" | tr -cd 'a-zA-Z0-9._-')
+BRANCH=$(printf '%s' "${RAW_BRANCH:-}" | tr '/' '-' | tr -cd 'a-zA-Z0-9._-')
 BRANCH="${BRANCH:-unknown}"
 echo "SLUG=$SLUG"
 echo "BRANCH=$BRANCH"