diff --git a/cartogram3.py b/cartogram3.py
index c2b724b..6602179 100644
--- a/cartogram3.py
+++ b/cartogram3.py
@@ -314,7 +314,7 @@ def run(self):
 
             # remember the input layer’s style
             self.inputLayerStyle = QDomDocument()
-            self.inputLayer.exportNamedStyle(self.inputLayerStyle, None)
+            self.inputLayer.exportNamedStyle(self.inputLayerStyle)
 
             # set up all widgets for status reporting
             self.progressBar = QProgressBar()