diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 282da5e..83f8289 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -5,6 +5,9 @@ on:
   push:
     branches: [ main ]
 
+permissions:
+  contents: read
+
 jobs:
   scan_ruby:
     runs-on: ubuntu-latest