diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1f4c6c5..8c3028a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
       - run: docker pull exercism/sml-test-runner
       - name: Run tests for all exercises
         run: sh ./bin/test