diff --git a/src/wp-includes/ms-functions.php b/src/wp-includes/ms-functions.php
index 8493b40b36..487d8401e5 100644
--- a/src/wp-includes/ms-functions.php
+++ b/src/wp-includes/ms-functions.php
@@ -494,6 +494,10 @@ function wpmu_validate_user_signup($user_name, $user_email) {
 	if ( strlen( $user_name ) < 4 )
 		$errors->add('user_name',  __( 'Username must be at least 4 characters.' ) );
 
+	if ( strlen( $user_name ) > 60 ) {
+		$errors->add( 'user_name', __( 'Username may not be longer than 60 characters.' ) );
+	}
+
 	if ( strpos( $user_name, '_' ) !== false )
 		$errors->add( 'user_name', __( 'Sorry, usernames may not contain the character &#8220;_&#8221;!' ) );
 
diff --git a/tests/phpunit/tests/multisite/wpmuValidateUserSignup.php b/tests/phpunit/tests/multisite/wpmuValidateUserSignup.php
index 914d938691..a368288d8c 100644
--- a/tests/phpunit/tests/multisite/wpmuValidateUserSignup.php
+++ b/tests/phpunit/tests/multisite/wpmuValidateUserSignup.php
@@ -26,6 +26,7 @@ class Tests_Multisite_WpmuValidateUserSignup extends WP_UnitTestCase {
 			array( 'f', 'User names of 1 characters are not allowed.'  ),
 			array( 'f', 'User names of 1 characters are not allowed.'  ),
 			array( '12345', 'User names consisting only of numbers are not allowed.'  ),
+			array( 'thisusernamecontainsenoughcharacterstobelongerthan60characters', 'User names longer than 60 characters are not allowed.' ),
 		);
 	}