diff --git a/libnotificationmanager/limitedrowcountproxymodel.cpp b/libnotificationmanager/limitedrowcountproxymodel.cpp
--- a/libnotificationmanager/limitedrowcountproxymodel.cpp
+++ b/libnotificationmanager/limitedrowcountproxymodel.cpp
@@ -34,8 +34,12 @@
 
 void LimitedRowCountProxyModel::setSourceModel(QAbstractItemModel *sourceModel)
 {
-    if (this->sourceModel()) {
-        disconnect(this->sourceModel(), nullptr, this, nullptr);
+    if (sourceModel == QAbstractProxyModel::sourceModel()) {
+        return;
+    }
+
+    if (QAbstractProxyModel::sourceModel()) {
+        disconnect(QAbstractProxyModel::sourceModel(), nullptr, this, nullptr);
     }
 
     QSortFilterProxyModel::setSourceModel(sourceModel);
diff --git a/libnotificationmanager/notificationgroupcollapsingproxymodel.cpp b/libnotificationmanager/notificationgroupcollapsingproxymodel.cpp
--- a/libnotificationmanager/notificationgroupcollapsingproxymodel.cpp
+++ b/libnotificationmanager/notificationgroupcollapsingproxymodel.cpp
@@ -36,8 +36,12 @@
 
 void NotificationGroupCollapsingProxyModel::setSourceModel(QAbstractItemModel *source)
 {
-    if (sourceModel()) {
-        disconnect(sourceModel(), nullptr, this, nullptr);
+    if (source == QAbstractProxyModel::sourceModel()) {
+        return;
+    }
+
+    if (QAbstractProxyModel::sourceModel()) {
+        disconnect(QAbstractProxyModel::sourceModel(), nullptr, this, nullptr);
     }
 
     QSortFilterProxyModel::setSourceModel(source);