diff --git a/problems/链表理论基础.md b/problems/链表理论基础.md
index 1a29c32a..8378f7f2 100644
--- a/problems/链表理论基础.md
+++ b/problems/链表理论基础.md
@@ -186,7 +186,7 @@ TypeScript:
 ```typescript
 class ListNode {
   public val: number;
-  public next: ListNode = null;
+  public next: ListNode|null = null;
   constructor(value: number) {
     this.val = value;
     this.next = null;