diff --git a/trl/trainer/kto_trainer.py b/trl/trainer/kto_trainer.py
index c57650939d..a34ad62d44 100644
--- a/trl/trainer/kto_trainer.py
+++ b/trl/trainer/kto_trainer.py
@@ -578,6 +578,7 @@ def make_inputs_require_grad(module, input, output):
                 "truncation_mode": self.truncation_mode,
                 "label_pad_token_id": self.label_pad_token_id,
                 "max_prompt_length": self.max_prompt_length,
+                "max_completion_length": self.max_completion_length,
             }
             train_dataset = train_dataset.map(
                 _process_tokens,
@@ -618,6 +619,7 @@ def make_inputs_require_grad(module, input, output):
                     "truncation_mode": self.truncation_mode,
                     "label_pad_token_id": self.label_pad_token_id,
                     "max_prompt_length": self.max_prompt_length,
+                    "max_completion_length": self.max_completion_length,
                 }
                 eval_dataset = eval_dataset.map(
                     _process_tokens,