diff --git a/python/0100-same-tree.py b/python/0100-same-tree.py
index 4d55e2588..29957cf4f 100644
--- a/python/0100-same-tree.py
+++ b/python/0100-same-tree.py
@@ -7,7 +7,7 @@
 
 
 class Solution:
-    def isSameTree(self, p: TreeNode, q: TreeNode) -> bool:
+    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
         if not p and not q:
             return True
         if p and q and p.val == q.val: