diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ad4b9f9..105491f 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -14,5 +14,6 @@ jobs:
       - name: PHPUnit tests
         uses: php-actions/phpunit@v3
         with:
+          version: "4.8.36"
           php_version: "7.3"