diff --git a/script/RobotTCP.py b/script/RobotTCP.py
index 11badb0..3bff3a9 100644
--- a/script/RobotTCP.py
+++ b/script/RobotTCP.py
@@ -251,7 +251,7 @@ class RobotTCP(TcpDevice, Stoppable):
             self.joint_forces = self.get_float_arr(6)            
             return self.joint_forces
         except:
-            return self.joint_forces = None
+            self.joint_forces = None
             raise
 
     def movej(self, joint_or_point, tool, desc):