diff --git a/src/gui/widgets/qmainwindow.cpp b/src/gui/widgets/qmainwindow.cpp
index c4dfefaf8..0a1bb1921 100644
--- a/src/gui/widgets/qmainwindow.cpp
+++ b/src/gui/widgets/qmainwindow.cpp
@@ -1203,8 +1203,7 @@ bool QMainWindow::restoreState(const QByteArray &state, int version)
 {
     if (state.isEmpty())
         return false;
-    QByteArray sd = state;
-    QDataStream stream(&sd, QIODevice::ReadOnly);
+    QDataStream stream(state);
     int marker, v;
     stream >> marker;
     stream >> v;