diff --git a/README.rst b/README.rst
index ff4b891..343410b 100644
--- a/README.rst
+++ b/README.rst
@@ -3,11 +3,11 @@ Captcha
 
 A captcha library that generates audio and image CAPTCHAs.
 
-.. image:: https://travis-ci.org/lepture/captcha.png?branch=master
+.. image:: https://travis-ci.org/lepture/captcha.svg?branch=master
    :target: https://travis-ci.org/lepture/captcha
-.. image:: https://ci.appveyor.com/api/projects/status/amm21f13lx4wuura
+.. image:: https://ci.appveyor.com/api/projects/status/amm21f13lx4wuura?svg=true
    :target: https://ci.appveyor.com/project/lepture/captcha
-.. image:: https://coveralls.io/repos/lepture/captcha/badge.png?branch=master
+.. image:: https://coveralls.io/repos/lepture/captcha/badge.svg?branch=master
    :target: https://coveralls.io/r/lepture/captcha