diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 7140894ed2..67d307cded 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -2219,6 +2219,10 @@ function update_usermeta( $user_id, $meta_key, $meta_value ) {
 	if ( is_array($meta_value) || is_object($meta_value) )
 		$meta_value = serialize($meta_value);
 	$meta_value = trim( $meta_value );
+	
+	if (empty($meta_value)) {
+		delete_usermeta($user_id, $meta_key);
+	}
 
 	$cur = $wpdb->get_row("SELECT * FROM $wpdb->usermeta WHERE user_id = '$user_id' AND meta_key = '$meta_key'");
 	if ( !$cur ) {