Use flat style gittip button

This matches the new markdown styling a bit better.

1 files changed, 1 insertions, 1 deletions

diff --git a/README.md b/README.md
index 36d4f3ef8..68b6a7d8b 100644
--- a/README.md
+++ b/README.md
@@ -36,7 +36,7 @@ Donations
 ---------
 We accept tips through [Gittip][tip].
 
-[![Gittip](http://img.shields.io/gittip/Homebrew.svg)](https://www.gittip.com/Homebrew/)
+[![Gittip](https://img.shields.io/gittip/Homebrew.svg?style=flat)](https://www.gittip.com/Homebrew/)
 
 [home]:http://brew.sh
 [wiki]:https://github.com/Homebrew/homebrew/wiki