diff --git a/qt6-after/qt6-migrated-legatus/Lts/DDS/FTC/generic_ftc_impl.h b/qt6-after/qt6-migrated-legatus/Lts/DDS/FTC/generic_ftc_impl.h
index 9e1627e62..aeb2ab06a 100644
--- a/qt6-after/qt6-migrated-legatus/Lts/DDS/FTC/generic_ftc_impl.h
+++ b/qt6-after/qt6-migrated-legatus/Lts/DDS/FTC/generic_ftc_impl.h
@@ -430,7 +430,10 @@ private:
           INFO_LOG(m_logger) << "#receiveReply for " << TopicNameHelper::replyTopicTypeName();
           // QueuedConnection to make sure the data is handled in the correct Qt (main) thread
           request.replySlot.invoke(m_objToInform, Qt::QueuedConnection,
-                                   QArgument<ReplyTopic>(TopicNameHelper::replyTopicTypeName(), reply.data()),  // need to explicitly specify the registered typename
+                                   // Qt6: QMetaMethod::invoke takes QMetaMethodArgument; pass the
+                                   // registered topic type name like Q_ARG does, but with the
+                                   // runtime name (ReplyTopic is a template parameter).
+                                   QtPrivate::Invoke::argument<ReplyTopic>(TopicNameHelper::replyTopicTypeName(), reply.data()),
                                    Q_ARG(int, request.uniqueId),
                                    Q_ARG(bool, !inProgress)); // finished yes/no
         }