diff --git a/.github/workflows/build_master.yml b/.github/workflows/build_master.yml
index 165fd5ea8..61daf614c 100644
--- a/.github/workflows/build_master.yml
+++ b/.github/workflows/build_master.yml
@@ -36,6 +36,7 @@ jobs:
         run: MDBOOK_BOOK__LANGUAGE=en mdbook build || (echo "Error logs" && cat hacktricks-preprocessor-error.log && echo "" && echo "" && echo "Debug logs" && (cat hacktricks-preprocessor.log | tail -n 20) && exit 1)
       
       - name: Update searchindex in repo (purge history, keep current on HEAD)
+        shell: bash
         run: |
           set -euo pipefail