diff --git a/interfaces/viewerinterface.h b/interfaces/viewerinterface.h
index 839a45395..9df974df1 100644
--- a/interfaces/viewerinterface.h
+++ b/interfaces/viewerinterface.h
@@ -13,7 +13,7 @@
 #include "../core/okular_export.h"
 
 #include <QtCore/QObject>
-#include <QString>
+#include <QtCore/QString>
 
 namespace Okular {