2 files changed, 3 insertions, 3 deletions
diff --git a/barchart.cpp b/barchart.cpp
index b0a367c..a4d9791 100644
--- a/barchart.cpp
+++ b/barchart.cpp
@@ -30,7 +30,7 @@ void BarChart::setValues(const arma::vec &values)
     emit valuesChanged(values);
 }
 
-QSGNode *BarChart::newBarNode()
+QSGNode *BarChart::newBarNode() const
 {
     // A bar node is:
     // opacityNode [outlineGeomNode barGeomNode]
diff --git a/barchart.h b/barchart.h
index ccbb13e..164e0eb 100644
--- a/barchart.h
+++ b/barchart.h
@@ -12,7 +12,7 @@ public:
     ~BarChart();
 
 signals:
-    void valuesChanged(const arma::vec &values);
+    void valuesChanged(const arma::vec &values) const;
 
 public slots:
     void setValues(const arma::vec &values);
@@ -23,7 +23,7 @@ protected:
     void mousePressEvent(QMouseEvent *event);
 
 private:
-    QSGNode *newBarNode();
+    QSGNode *newBarNode() const;
     void updateBarNodeGeom(QSGNode *barNode, float x, float width, float height);
     void updateBars(QSGNode *root);