diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a99ea84..60d5096 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,7 +7,7 @@ jobs:
   docs:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2.3.0
     - uses: ammaraskar/sphinx-action@0.4
       with:
         docs-folder: "."
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