diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index a2f15c0..6a1490a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -1,5 +1,7 @@
 name: CI Test
 on: [push, pull_request]
+permissions:
+  contents: read
 jobs:
   build:
     name: Ruby ${{ matrix.ruby }}