diff --git a/src/llamafactory/data/template.py b/src/llamafactory/data/template.py
index b91f9c1d4..c4f21b8ee 100644
--- a/src/llamafactory/data/template.py
+++ b/src/llamafactory/data/template.py
@@ -1113,7 +1113,7 @@ register_template(
 register_template(
     name="gpt_oss",
     format_user=StringFormatter(slots=["<|start|>user<|message|>{{content}}<|end|><|start|>assistant"]),
-    format_assistant=StringFormatter(slots=["{{content}}<|end|>"]),
+    format_assistant=StringFormatter(slots=["{{content}}"]),
     format_system=StringFormatter(slots=["<|start|>system<|message|>{{content}}<|end|>"]),
     default_system="You are ChatGPT, a large language model trained by OpenAI.",
     thought_words=("<|channel|>analysis<|message|>", "<|end|><|start|>assistant<|channel|>final<|message|>"),