diff --git a/.github/workflows/phpstan.yml b/.github/workflows/phpstan.yml
index b0cde6a..16301c9 100644
--- a/.github/workflows/phpstan.yml
+++ b/.github/workflows/phpstan.yml
@@ -20,7 +20,7 @@ jobs:
           coverage: none
 
       - name: Install composer dependencies
-        uses: ramsey/composer-install@v3
+        uses: ramsey/composer-install@3cf229dc2919194e9e36783941438d17239e8520 # 3.1.1
 
       - name: Run PHPStan
         run: ./vendor/bin/phpstan --error-format=github