diff --git a/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTest.php
index 0458c54..f0004fa 100644
--- a/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTest.php
@@ -19,7 +19,10 @@ class MigrateCommentTest extends MigrateDrupal6TestBase {
 
   use CommentTestTrait;
 
-  static $modules = array('node', 'comment', 'text', 'filter');
+  // Directly testing that comments' entity_id is populated upon importing is
+  // not straightforward, but RDF module serves as an implicit test;
+  // its hook_comment_storage_load() references $comment->getCommentedEntity().
+  static $modules = ['node', 'comment', 'text', 'filter', 'rdf'];
 
   /**
    * {@inheritdoc}