diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index e277d710c4..309a4934fe 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -543,7 +543,6 @@ function wpmu_validate_user_signup($user_name, $user_email) {
 function wpmu_validate_blog_signup($blogname, $blog_title, $user = '') {
 	global $wpdb, $domain, $base, $current_site;
 
-	$blogname = preg_replace( "/\s+/", '', sanitize_user( $blogname, true ) );
 	$blog_title = strip_tags( $blog_title );
 	$blog_title = substr( $blog_title, 0, 50 );