diff --git a/src/open_r1/grpo.py b/src/open_r1/grpo.py
index 1970f8ef..f9a07e2c 100644
--- a/src/open_r1/grpo.py
+++ b/src/open_r1/grpo.py
@@ -99,7 +99,7 @@ class GRPOScriptArguments(ScriptArguments):
 
 
 SYSTEM_PROMPT = (
-    "A conversation between User and Assistant. The user asks a question, and the Assistant solves it. The assistant "
+    "A conversation between user and assistant. The user asks a question, and the assistant solves it. The assistant "
     "first thinks about the reasoning process in the mind and then provides the user with the answer. The reasoning "
     "process and answer are enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., "
     "<think> reasoning process here </think><answer> answer here </answer>"