diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 19ebd401..ac4a887e 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -7,6 +7,9 @@ on:
     branches: [ main ]
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   test:
     name: Test on ${{ matrix.os }} / Python ${{ matrix.python-version }}