diff --git a/script/devices/Hexiposi.py b/script/devices/Hexiposi.py
index aff08e0..b81b238 100644
--- a/script/devices/Hexiposi.py
+++ b/script/devices/Hexiposi.py
@@ -120,7 +120,7 @@ class Hexiposi(DiscretePositionerBase):
 
 
     def assert_in_position(self, pos):
-        if not is_in_position(pos):
+        if not self.is_in_position(pos):
             raise Exception ("Hexiposi is not in position")
     
     def assert_homed(self):