diff --git a/doc/3.3.6_heap_exploit_1.md b/doc/3.3.6_heap_exploit_1.md
index 4888081..4f730af 100644
--- a/doc/3.3.6_heap_exploit_1.md
+++ b/doc/3.3.6_heap_exploit_1.md
@@ -622,7 +622,7 @@ BK->fd = FD
 ```
 chunk0_ptr = P = P->fd
 ```
-成功地修改了 chunk0_ptr，这时 `chunk0_ptr` 和 `chunk0_ptr[3]` 实际上就是同一东西：
+成功地修改了 chunk0_ptr，这时 `chunk0_ptr[0]` 和 `chunk0_ptr[3]` 实际上就是同一东西：
 ```
 gef➤  x/40gx 0x602010-0x10
 0x602000:	0x0000000000000000	0x0000000000000091  <-- chunk 0