diff --git a/README_zh.md b/README_zh.md
index b1a102c9..891df222 100644
--- a/README_zh.md
+++ b/README_zh.md
@@ -13,8 +13,6 @@ pocketpy是一个轻量级的Python解释器，为嵌入至游戏引擎而设计
 
 你可以 [在浏览器中体验](https://pocketpy.dev/static/web/) pocketpy的交互式界面（REPL）。
 
-<a href="https://www.buymeacoffee.com/blueloveTH"><img src="https://img.buymeacoffee.com/button-api/?text=Buy me a coffee&emoji=&slug=blueloveTH&button_colour=FF5F5F&font_colour=ffffff&font_family=Bree&outline_colour=000000&coffee_colour=FFDD00" /></a>
-
 ## 快速上手
 
 你可以在 [Github Release](https://github.com/blueloveTH/pocketpy/releases) 页面下载`pocketpy.h`，
diff --git a/docs/features/differences.md b/docs/features/differences.md
index 8bfc40e8..66f310d8 100644
--- a/docs/features/differences.md
+++ b/docs/features/differences.md
@@ -41,4 +41,5 @@ The easiest way to test a feature is to [try it on your browser](https://pocketp
 6. `__ne__` is not required. Define `__eq__` is enough.
 7. Raw string cannot have boundary quotes in it, even escaped. See [#55](https://github.com/blueloveTH/pocketpy/issues/55).
 8. In a starred unpacked assignment, e.g. `a, b, *c = x`, the starred variable can only be presented in the last position. `a, *b, c = x` is not supported.
-9. `a < b < c` does not work as you expected. Use `a < b and b < c` instead. **(available in main branch now)**
\ No newline at end of file
+9. `a < b < c` does not work as you expected. Use `a < b and b < c` instead. **(available in main branch now)**
+10. A `Tab` is equivalent to 4 spaces. You can mix `Tab` and spaces in indentation, but it is not recommended.
\ No newline at end of file
diff --git a/docs/index.md b/docs/index.md
index af33a3b5..275a200f 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -28,4 +28,4 @@ print(primes)
 
 ## Sponsor me
 
-https://github.com/sponsors/blueloveTH
+You can sponsor me via [Github Sponsors](https://github.com/sponsors/blueloveTH).