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--- a/README.md
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@@ -2,7 +2,7 @@
 
 pup is a command line tool for processing HTML. It reads from stdin,
 prints to stdout, and allows the user to filter parts of the page using
-[CSS selectors](http://www.w3schools.com/cssref/css_selectors.asp).
+[CSS selectors](https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Getting_started/Selectors).
 
 Inspired by [jq](http://stedolan.github.io/jq/), pup aims to be a
 fast and flexible way of exploring HTML from the terminal.