diff --git a/ci/ruby.yml b/ci/ruby.yml
index d8e672abe6..256aa1455c 100644
--- a/ci/ruby.yml
+++ b/ci/ruby.yml
@@ -13,6 +13,9 @@ on:
   pull_request:
     branches: [ $default-branch ]
 
+permissions:
+  contents: read
+
 jobs:
   test: