diff --git a/src/platformtheme/kdeplatformsystemtrayicon.h b/src/platformtheme/kdeplatformsystemtrayicon.h
--- a/src/platformtheme/kdeplatformsystemtrayicon.h
+++ b/src/platformtheme/kdeplatformsystemtrayicon.h
@@ -47,6 +47,7 @@
     void syncSeparatorsCollapsible(bool enable) override;
     quintptr tag() const override;
     QPlatformMenuItem *createMenuItem() const override;
+    QPlatformMenu *createSubMenu() const override;
 
     QMenu *menu() const;
 
diff --git a/src/platformtheme/kdeplatformsystemtrayicon.cpp b/src/platformtheme/kdeplatformsystemtrayicon.cpp
--- a/src/platformtheme/kdeplatformsystemtrayicon.cpp
+++ b/src/platformtheme/kdeplatformsystemtrayicon.cpp
@@ -47,6 +47,11 @@
     return new SystemTrayMenuItem();
 }
 
+QPlatformMenu *SystemTrayMenu::createSubMenu() const
+{
+    return new SystemTrayMenu();
+}
+
 void SystemTrayMenu::insertMenuItem(QPlatformMenuItem *menuItem, QPlatformMenuItem *before)
 {
     if (SystemTrayMenuItem *ours = qobject_cast<SystemTrayMenuItem*>(menuItem)) {