diff --git a/docs/chapter_tree/avl_tree.md b/docs/chapter_tree/avl_tree.md
index 0b37a726f..3d9018677 100644
--- a/docs/chapter_tree/avl_tree.md
+++ b/docs/chapter_tree/avl_tree.md
@@ -180,7 +180,7 @@ AVL 树既是二叉搜索树，也是平衡二叉树，同时满足这两类二
 
     ```c title=""
     /* AVL 树节点结构体 */
-    TreeNode struct TreeNode {
+    typedef struct TreeNode {
         int val;
         int height;
         struct TreeNode *left;