diff --git a/python/sglang/lang/tracer.py b/python/sglang/lang/tracer.py
index cfe9198bc..69f035b07 100644
--- a/python/sglang/lang/tracer.py
+++ b/python/sglang/lang/tracer.py
@@ -278,6 +278,6 @@ class TracingScope:
 
     def add_child_state(self, state: TracerProgramState):
         cur_scope = self
-        while cur_scope != None:
+        while cur_scope is not None:
             cur_scope.tracer_state.child_states.append(state)
             cur_scope = cur_scope.last_scope