diff --git a/rllib/agents/trainer.py b/rllib/agents/trainer.py
index a404e7ecb..02462f3c4 100644
--- a/rllib/agents/trainer.py
+++ b/rllib/agents/trainer.py
@@ -1053,7 +1053,9 @@ class Trainer(Trainable):
             raise ValueError("`model._time_major` only supported "
                              "iff `_use_trajectory_view_api` is True!")
 
-        if type(config["input_evaluation"]) != list:
+        if isinstance(config["input_evaluation"], tuple):
+            config["input_evaluation"] = list(config["input_evaluation"])
+        elif not isinstance(config["input_evaluation"], list):
             raise ValueError(
                 "`input_evaluation` must be a list of strings, got {}!".format(
                     config["input_evaluation"]))