diff --git a/wolfsheep.py b/wolfsheep.py
index 04f4705..ff8a831 100644
--- a/wolfsheep.py
+++ b/wolfsheep.py
@@ -32,12 +32,12 @@ class Simulator:
             for obj in state.right:
                 nextStates.append( Model(state.left | set([Model.Man, obj]) , state.right - set([Model.Man,obj]) ) )
 
-        nextStates = list(filter(
+        nextStates = filter(
                 lambda s: not(
                     s in stack or
                     any([ any([ invalid_state <= m for invalid_state in Simulator.invalid_states ]) and Model.Man not in m for m in [s.left,s.right] ])
                 )
-            , nextStates)) #Remove invalid and previous states.
+            , nextStates) #Remove invalid and previous states.
 
         for s in nextStates:
             m = self.simulate(s,stack)