diff --git a/src/Faker/Container/Container.php b/src/Faker/Container/Container.php
index 409a7406a0..4bba4d1df8 100644
--- a/src/Faker/Container/Container.php
+++ b/src/Faker/Container/Container.php
@@ -81,7 +81,7 @@ public function get($id): Extension
      *
      * @param callable|object|string $definition
      */
-    private function getService($id, $definition)
+    private function getService(string $id, $definition)
     {
         if (is_callable($definition)) {
             try {