diff --git a/metastable_baselines2/trpl/trpl.py b/metastable_baselines2/trpl/trpl.py
index 043341a..c1329e8 100644
--- a/metastable_baselines2/trpl/trpl.py
+++ b/metastable_baselines2/trpl/trpl.py
@@ -203,7 +203,8 @@ class TRPL(BetterOnPolicyAlgorithm):
         # Update optimizer learning rate
         self._update_learning_rate(self.policy.optimizer)
         # Compute current clip range
-        clip_range = self.clip_range(self._current_progress_remaining)
+        if self.clip_range is not None:
+            clip_range = self.clip_range(self._current_progress_remaining)
         # Optional: clip range for the value function
         if self.clip_range_vf is not None:
             clip_range_vf = self.clip_range_vf(self._current_progress_remaining)