diff --git a/envs.py b/envs.py
index 1dc2d91..f8592bb 100644
--- a/envs.py
+++ b/envs.py
@@ -87,7 +87,7 @@ def _get_val(self):
 
   def _trade(self, action):
     # all combo to sell(0), hold(1), or buy(2) stocks
-    action_combo = map(list, itertools.product([0, 1, 2], repeat=self.n_stock))
+    action_combo = list(map(list, itertools.product([0, 1, 2], repeat=self.n_stock)))
     action_vec = action_combo[action]
 
     # one pass to get sell/buy index