diff --git a/README.md b/README.md
index 195925f..964ac80 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,7 @@ core-icons
 =========
 
 See the [component page](http://polymer-project.org/docs/elements/core-elements.html#core-icons) for more information.
+
+## Building
+Running `update-icons.sh` will checkout [material-design-icons](https://github.com/google/material-design-icons), reduce
+the fileset to 24px svgs, and compile the iconsets.