diff --git a/README.md b/README.md
index e96f5b010..9fbde4295 100644
--- a/README.md
+++ b/README.md
@@ -189,9 +189,11 @@ GitBook will read the `.gitignore`, `.bookignore` and `.ignore` files to get a l
 
 #### Cover
 
-A cover image can be set by creating a file: **/cover.jpg** or **cover.png**.
+A cover image can be set by creating a file: **/cover.jpg**.
 The best resolution is **1800x2360**. The generation of the cover can be done automatically using the plugin [autocover](https://github.com/GitbookIO/plugin-autocover).
 
+A small version of the cover can also be set by creating a file: **/cover_small.jpg**.
+
 #### Plugins
 
 Plugins can used to extend your book's functionality. Read [GitbookIO/plugin](https://github.com/GitbookIO/plugin) for more information about how to build a plugin for gitbook.