diff --git a/lib/caditem.py b/lib/caditem.py
index f4146e6..5e6510e 100644
--- a/lib/caditem.py
+++ b/lib/caditem.py
@@ -182,7 +182,10 @@ class CadItem():
             self.gui_data[key] = val
 
     def get_gui_data(self, key):
-        return self.gui_data[key]
+        if key in self.gui_data:
+            return self.gui_data[key]
+        else:
+            return None
     def get_all_gui_data(self):
         return self.gui_data