diff --git a/messageviewer/src/interfaces/bodypart.h b/messageviewer/src/interfaces/bodypart.h
--- a/messageviewer/src/interfaces/bodypart.h
+++ b/messageviewer/src/interfaces/bodypart.h
@@ -34,8 +34,8 @@
 #ifndef __KMAIL_INTERFACES_BODYPART_H__
 #define __KMAIL_INTERFACES_BODYPART_H__
 
-class QByteArray;
-class QString;
+#include <QByteArray>
+#include <QString>
 
 namespace KMime
 {