diff --git a/metastable_baselines2/trpl/trpl.py b/metastable_baselines2/trpl/trpl.py
index 83d78ab..94a020f 100644
--- a/metastable_baselines2/trpl/trpl.py
+++ b/metastable_baselines2/trpl/trpl.py
@@ -114,6 +114,8 @@ class TRPL(BetterOnPolicyAlgorithm):
         _init_setup_model: bool = True,
     ):
         self.projection_class = castProjection(projection_class)
+        if projection_kwargs is None:
+            projection_kwargs = {}
         self.projection_kwargs = projection_kwargs
         self.projection = self.projection_class(**self.projection_kwargs)
         if policy_kwargs is None: