diff --git a/nnabla_rl/__init__.py b/nnabla_rl/__init__.py
index bd9971ee..fe908954 100644
--- a/nnabla_rl/__init__.py
+++ b/nnabla_rl/__init__.py
@@ -1,5 +1,5 @@
 # Copyright 2020,2021 Sony Corporation.
-# Copyright 2021,2022,2023 Sony Group Corporation.
+# Copyright 2021,2022,2023,2024 Sony Group Corporation.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = '0.15.0.dev1'
+__version__ = '0.16.0.dev1'
 
 from nnabla_rl.logger import enable_logging, disable_logging  # noqa
 from nnabla_rl.scopes import eval_scope, is_eval_scope  # noqa
diff --git a/nnabla_rl/model_trainers/policy/amp_policy_trainer.py b/nnabla_rl/model_trainers/policy/amp_policy_trainer.py
index 22c4609f..61e27e25 100644
--- a/nnabla_rl/model_trainers/policy/amp_policy_trainer.py
+++ b/nnabla_rl/model_trainers/policy/amp_policy_trainer.py
@@ -172,6 +172,6 @@ def _setup_training_variables(self, batch_size) -> TrainingVariables:
         extra["advantage"] = advantage_var
         return TrainingVariables(batch_size, s_current_var, a_current_var, extra=extra)
 
-    @ property
+    @property
     def loss_variables(self) -> Dict[str, nn.Variable]:
         return {"pi_loss": self._pi_loss}