diff --git a/panels/dock/taskmanager/abstractwindowmonitor.cpp b/panels/dock/taskmanager/abstractwindowmonitor.cpp
index 0ed02a5f2..55af58ad0 100644
--- a/panels/dock/taskmanager/abstractwindowmonitor.cpp
+++ b/panels/dock/taskmanager/abstractwindowmonitor.cpp
@@ -101,8 +101,8 @@ void AbstractWindowMonitor::destroyWindow(AbstractWindow * window)
     if (pos == -1)
         return;
 
-    beginRemoveRows(QModelIndex(), pos, pos + 1);
-    m_trackedWindows.removeOne(window);
+    beginRemoveRows(QModelIndex(), pos, pos);
+    m_trackedWindows.removeAt(pos);
     endRemoveRows();
 }