diff --git a/applets/systemtray/systemtraymodel.cpp b/applets/systemtray/systemtraymodel.cpp
--- a/applets/systemtray/systemtraymodel.cpp
+++ b/applets/systemtray/systemtraymodel.cpp
@@ -265,6 +265,12 @@
 
 void SystemTrayModel::addSourceModel(QAbstractItemModel *sourceModel)
 {
-    m_roleNames.unite(sourceModel->roleNames());
+    QHash<int, QByteArray> roleNames = sourceModel->roleNames();
+    for (const int key : roleNames.keys()) {
+        if (!m_roleNames.contains(key)) {
+            m_roleNames.insert(key, roleNames.value(key));
+        }
+    }
+
     KConcatenateRowsProxyModel::addSourceModel(sourceModel);
 }