diff --git a/src/plugins/qmldesigner/designercore/include/modelnode.h b/src/plugins/qmldesigner/designercore/include/modelnode.h
index abb0300bb89..9dd636be625 100644
--- a/src/plugins/qmldesigner/designercore/include/modelnode.h
+++ b/src/plugins/qmldesigner/designercore/include/modelnode.h
@@ -173,7 +173,7 @@ public:
     static int variantUserType();
     QVariant toVariant() const;
 
-    QVariant auxiliaryData(const PropertyName &name) const;
+    const QVariant auxiliaryData(const PropertyName &name) const;
     void setAuxiliaryData(const PropertyName &name, const QVariant &data) const;
     void removeAuxiliaryData(const PropertyName &name) const;
     bool hasAuxiliaryData(const PropertyName &name) const;
diff --git a/src/plugins/qmldesigner/designercore/model/modelnode.cpp b/src/plugins/qmldesigner/designercore/model/modelnode.cpp
index b078af6aef8..14ca4a67bfe 100644
--- a/src/plugins/qmldesigner/designercore/model/modelnode.cpp
+++ b/src/plugins/qmldesigner/designercore/model/modelnode.cpp
@@ -991,7 +991,7 @@ QVariant ModelNode::toVariant() const
     return QVariant::fromValue(*this);
 }
 
-QVariant ModelNode::auxiliaryData(const PropertyName &name) const
+const QVariant ModelNode::auxiliaryData(const PropertyName &name) const
 {
     if (!isValid())
         throw InvalidModelNodeException(__LINE__, __FUNCTION__, __FILE__);