diff --git a/src/wp-includes/user.php b/src/wp-includes/user.php
index f60dbe5d3f..5723031637 100644
--- a/src/wp-includes/user.php
+++ b/src/wp-includes/user.php
@@ -2170,7 +2170,7 @@ function wp_insert_user( $userdata ) {
 	$user_login = trim( $pre_user_login );
 
 	// user_login must be between 0 and 60 characters.
-	if ( empty( $user_login ) ) {
+	if ( empty( sanitize_user( $user_login ) ) ) {
 		return new WP_Error( 'empty_user_login', __( 'Cannot create a user with an empty login name.' ) );
 	} elseif ( mb_strlen( $user_login ) > 60 ) {
 		return new WP_Error( 'user_login_too_long', __( 'Username may not be longer than 60 characters.' ) );