diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 79ee0c1..7343902 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -5,6 +5,10 @@ on:
     branches: [main]
   pull_request:
 
+# CI only checks out and builds — lock the GITHUB_TOKEN to read-only.
+permissions:
+  contents: read
+
 jobs:
   check:
     runs-on: ubuntu-latest