diff --git a/wp-includes/pluggable.php b/wp-includes/pluggable.php
index 8fb04d3376..595d102c82 100644
--- a/wp-includes/pluggable.php
+++ b/wp-includes/pluggable.php
@@ -102,6 +102,9 @@ if ( !function_exists('get_userdata') ) :
  */
 function get_userdata( $user_id ) {
 	global $wpdb;
+
+	if ( ! is_numeric( $user_id ) )
+		return false;
 		
 	$user_id = absint( $user_id );
 	if ( ! $user_id )