diff --git a/plugins/plasma/pimeventsplugin/eventdatavisitor.cpp b/plugins/plasma/pimeventsplugin/eventdatavisitor.cpp
index 065d368be0e8a99cbbf74455b0d39904b56f2983..5c80f69a12ebca8a721c822d06da3cbcf94d8ae5 100644
--- a/plugins/plasma/pimeventsplugin/eventdatavisitor.cpp
+++ b/plugins/plasma/pimeventsplugin/eventdatavisitor.cpp
@@ -135,7 +135,7 @@ EventDataVisitor::~EventDataVisitor()
 }
 
 
-QMultiHash<QDate, CalendarEvents::EventData> EventDataVisitor::results() const
+const QMultiHash<QDate, CalendarEvents::EventData> &EventDataVisitor::results() const
 {
     return mResults;
 }
@@ -204,7 +204,7 @@ EventDataIdVisitor::EventDataIdVisitor(Akonadi::ETMCalendar *calendar, const QDa
 {
 }
 
-QStringList EventDataIdVisitor::results() const
+const QStringList &EventDataIdVisitor::results() const
 {
     return mResults;
 }
diff --git a/plugins/plasma/pimeventsplugin/eventdatavisitor.h b/plugins/plasma/pimeventsplugin/eventdatavisitor.h
index b146c58f61bc51ed8ffc66bf29005a958029d37a..8a0a7b8f66f2c4058d3aeaa00e3d6ae980d0a948 100644
--- a/plugins/plasma/pimeventsplugin/eventdatavisitor.h
+++ b/plugins/plasma/pimeventsplugin/eventdatavisitor.h
@@ -59,7 +59,7 @@ public:
     EventDataVisitor(Akonadi::ETMCalendar *calendar, const QDate &start, const QDate &end);
     ~EventDataVisitor();
 
-    QMultiHash<QDate, CalendarEvents::EventData> results() const;
+    const QMultiHash<QDate, CalendarEvents::EventData> &results() const;
 
 protected:
     bool visit(const KCalCore::Event::Ptr &event) Q_DECL_OVERRIDE;
@@ -79,7 +79,7 @@ class EventDataIdVisitor : public BaseEventDataVisitor
 public:
     explicit EventDataIdVisitor(Akonadi::ETMCalendar *calendar, const QDate &start, const QDate &end);
 
-    QStringList results() const;
+    const QStringList &results() const;
 
 protected:
     bool visit(const KCalCore::Event::Ptr &event) Q_DECL_OVERRIDE;