diff --git a/attack_grey_box.py b/attack_grey_box.py
index 1f3a2ef..cc800a7 100644
--- a/attack_grey_box.py
+++ b/attack_grey_box.py
@@ -77,7 +77,7 @@
         attack = attack_class(
             model, 
             epsilon=args['bbox_epsilon'],                  
-            step_size=5*args['epsilon_eval']/args['num_steps_eval'], 
+            step_size=5*args['bbox_epsilon']/args['num_steps_eval'], 
             num_steps=args['num_steps_eval']
         )
     else: