diff --git a/.github/workflows/ci-post-merge.yml b/.github/workflows/ci-post-merge.yml
index 1ee97b591..6d76301d8 100644
--- a/.github/workflows/ci-post-merge.yml
+++ b/.github/workflows/ci-post-merge.yml
@@ -4,6 +4,9 @@ on:
   push:
     branches: [master]
 
+permissions:
+  contents: read  #  to fetch code (actions/checkout)
+
 jobs:
   build_and_test_nightly:
     strategy: