diff --git a/src/com/fr/plugin/demo/DemoChart.java b/src/com/fr/plugin/demo/DemoChart.java
index f06a0ae..05c6818 100644
--- a/src/com/fr/plugin/demo/DemoChart.java
+++ b/src/com/fr/plugin/demo/DemoChart.java
@@ -56,7 +56,9 @@ public class DemoChart extends AbstractChart<DemoDataConfig>{
     @Override
     public Object clone() throws CloneNotSupportedException {
         DemoChart result = (DemoChart) super.clone();
-        result.setTitleFormula(this.getTitleFormula().clone());
+        if (getTitleFormula() != null) {
+            result.setTitleFormula(this.getTitleFormula().clone());
+        }
         return result;
     }