diff -u b/core/modules/media/tests/src/Kernel/MediaSourceTest.php b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
--- b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
+++ b/core/modules/media/tests/src/Kernel/MediaSourceTest.php
@@ -483,7 +483,7 @@
   /**
    * Creates a media type via form submit.
    *
-   * @param int $source_plugin_id
+   * @param string $source_plugin_id
    *   Source plugin ID.
    * @param string $field_name
    *   Source field name.