diff --git a/www/includes/config.inc.php b/www/includes/config.inc.php
index 0d22d13..6bff5c7 100644
--- a/www/includes/config.inc.php
+++ b/www/includes/config.inc.php
@@ -40,7 +40,7 @@
  $SITE_NAME = (getenv('SITE_NAME') ? getenv('SITE_NAME') : 'LDAP user manager');
 
  $USERNAME_FORMAT = (getenv('USERNAME_FORMAT') ? getenv('USERNAME_FORMAT') : '{first_name}-{last_name}');
- $USERNAME_REGEX = '^[a-z][a-zA-Z0-9\._-]{3,32}$';
+ $USERNAME_REGEX = (getenv('USERNAME_REGEX') ? getenv('USERNAME_REGEX') : '^[a-z][a-zA-Z0-9\._-]{3,32}$');
  #We'll use the username regex for groups too.
 
  $PASSWORD_HASH = (getenv('PASSWORD_HASH') ? getenv('PASSWORD_HASH') : 'SSHA');