diff --git a/GitBook.gitignore b/GitBook.gitignore
index 333873a..7cb665f 100644
--- a/GitBook.gitignore
+++ b/GitBook.gitignore
@@ -1,31 +1,36 @@
 # Logs
 logs
 *.log
 
 # Runtime data
 pids
 *.pid
 *.seed
 
 # Directory for instrumented libs generated by jscoverage/JSCover
 lib-cov
 
 # Coverage directory used by tools like istanbul
 coverage
 
 # Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)
 .grunt
 
 # Compiled binary addons (http://nodejs.org/api/addons.html)
 build/Release
 
 # Dependency directory
 # Commenting this out is preferred by some people, see
 # https://npmjs.org/doc/faq.html#Should-I-check-my-node_modules-folder-into-git
 node_modules
 
 # Users Environment Variables
 .lock-wscript
 
 # Book build output
 _book
+
+# eBook build output
+*.epub
+*.mobi
+*.pdf