diff --git a/force_bdss/mco/i_multi_criteria_optimizers.py b/force_bdss/mco/i_multi_criteria_optimizers.py
index 9bb929a67f1d9b3e429b80dc8727f5cb2a4b3df5..93c6b25dca4f73afc08caa0d348c59b9a2e195eb 100644
--- a/force_bdss/mco/i_multi_criteria_optimizers.py
+++ b/force_bdss/mco/i_multi_criteria_optimizers.py
@@ -1,4 +1,4 @@
-from traits.api import Interface, String, Instance
+from traits.api import Interface, String
 
 
 class IMultiCriteriaOptimizer(Interface):