diff --git a/freqtrade/freqai/prediction_models/ReinforcementLearner_multiproc.py b/freqtrade/freqai/prediction_models/ReinforcementLearner_multiproc.py
index 9f0b2d436..f014da602 100644
--- a/freqtrade/freqai/prediction_models/ReinforcementLearner_multiproc.py
+++ b/freqtrade/freqai/prediction_models/ReinforcementLearner_multiproc.py
@@ -2,7 +2,8 @@ import logging
 from typing import Any, Dict
 
 from pandas import DataFrame
-from stable_baselines3.common.callbacks import EvalCallback
+from sb3_contrib.common.maskable.callbacks import MaskableEvalCallback
+from sb3_contrib.common.maskable.utils import is_masking_supported
 from stable_baselines3.common.vec_env import SubprocVecEnv, VecMonitor
 
 from freqtrade.freqai.data_kitchen import FreqaiDataKitchen
@@ -55,9 +56,11 @@ class ReinforcementLearner_multiproc(ReinforcementLearner):
                                                            env_info=env_info) for i
                                                   in range(self.max_threads)]))
 
-        self.eval_callback = EvalCallback(self.eval_env, deterministic=True,
-                                          render=False, eval_freq=eval_freq,
-                                          best_model_save_path=str(dk.data_path))
+        self.eval_callback = MaskableEvalCallback(self.eval_env, deterministic=True,
+                                                  render=False, eval_freq=eval_freq,
+                                                  best_model_save_path=str(dk.data_path),
+                                                  use_masking=(self.model_type == 'MaskablePPO' and
+                                                               is_masking_supported(self.eval_env)))
 
         # TENSORBOARD CALLBACK DOES NOT RECOMMENDED TO USE WITH MULTIPLE ENVS,
         # IT WILL RETURN FALSE INFORMATIONS, NEVERTHLESS NOT THREAD SAFE WITH SB3!!!