diff --git a/library/HTMLPurifier/ConfigSchema/schema/HTML.CustomDoctype.txt b/library/HTMLPurifier/ConfigSchema/schema/HTML.CustomDoctype.txt
index a64e3d7c..6ed70b59 100644
--- a/library/HTMLPurifier/ConfigSchema/schema/HTML.CustomDoctype.txt
+++ b/library/HTMLPurifier/ConfigSchema/schema/HTML.CustomDoctype.txt
@@ -4,6 +4,6 @@ VERSION: 2.0.1
 DEFAULT: NULL
 --DESCRIPTION--
 
-A custom doctype for power-users who defined there own document
+A custom doctype for power-users who defined their own document
 type. This directive only applies when %HTML.Doctype is blank.
 --# vim: et sw=4 sts=4