diff --git a/src/wp-admin/network/site-new.php b/src/wp-admin/network/site-new.php
index 37a266be6a..150ea3d4ef 100644
--- a/src/wp-admin/network/site-new.php
+++ b/src/wp-admin/network/site-new.php
@@ -42,6 +42,8 @@ if ( isset( $_REQUEST['action'] ) && 'add-site' == $_REQUEST['action'] ) {
 
 	$blog   = $_POST['blog'];
 	$domain = '';
+
+	$blog['domain'] = trim( $blog['domain'] );
 	if ( preg_match( '|^([a-zA-Z0-9-])+$|', $blog['domain'] ) ) {
 		$domain = strtolower( $blog['domain'] );
 	}