diff --git a/lib/stages/prepare_build.sh b/lib/stages/prepare_build.sh
index ab6bf34..15e22ef 100644
--- a/lib/stages/prepare_build.sh
+++ b/lib/stages/prepare_build.sh
@@ -78,4 +78,5 @@ _stage_prepare_build() {
     composer config allow-plugins.dealerdirect/phpcodesniffer-composer-installer true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
     composer config allow-plugins.phpstan/extension-installer true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
     composer config allow-plugins.php-http/discovery true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"
+    composer config allow-plugins.symfony/runtime true --no-plugins --working-dir="${DRUPAL_TESTING_DRUPAL_INSTALLATION_DIRECTORY}"   
 }