diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b54e6f6b..921d3ff9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -44,7 +44,7 @@ jobs:
         run: "composer config platform.php ${{ matrix.php-version }}"
 
       - name: "Install dependencies"
-        uses: "ramsey/composer-install@v3"
+        uses: "ramsey/composer-install@65e4f84970763564f46a70b8a54b90d033b3bdda" # 4.0.0
         with:
           dependency-versions: "${{ matrix.dependencies }}"