diff --git a/space_view3d_panel_measure.py b/space_view3d_panel_measure.py
index 436fc30f448ea656d65d7f36ca8893cbc18d8c8c..e7f0612ed8a7d6722eee221b93b39d808f550749 100644
--- a/space_view3d_panel_measure.py
+++ b/space_view3d_panel_measure.py
@@ -607,7 +607,7 @@ class VIEW3D_OT_display_measurements(bpy.types.Operator):
 
     def execute(self, context):
         if context.area.type == 'VIEW_3D':
-            mgr_ops = context.manager.operators.values();
+            mgr_ops = context.manager.operators.values()
             if not self.bl_idname in [op.bl_idname for op in mgr_ops]:
                 # Add the region OpenGL drawing callback
                 for WINregion in context.area.regions: