diff --git a/Source/WTF/wtf/text/WTFString.h b/Source/WTF/wtf/text/WTFString.h
index fa150bb666646..9cc165c20ded7 100644
--- a/Source/WTF/wtf/text/WTFString.h
+++ b/Source/WTF/wtf/text/WTFString.h
@@ -39,6 +39,8 @@
 QT_BEGIN_NAMESPACE
 class QString;
 class QStringView;
+class QLatin1StringView;
+class QByteArrayView;
 QT_END_NAMESPACE
 #endif