Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 19170)
+++ wp-includes/user.php	(working copy)
@@ -652,6 +652,12 @@
 function get_blogs_of_user( $user_id, $all = false ) {
 	global $wpdb;
 
+	$user_id = (int) $user_id;
+
+	// Logged out users can't have blogs
+	if ( empty( $user_id ) )
+		return false;
+
 	if ( ! is_multisite() ) {
 		$blog_id = get_current_blog_id();
 		$blogs = array( $blog_id => new stdClass );
@@ -664,12 +670,6 @@
 		return $blogs;
 	}
 
-	$user_id = (int) $user_id;
-
-	// Logged out users can't have blogs
-	if ( empty( $user_id ) )
-		return false;
-
 	$keys = get_user_meta( $user_id );
 	if ( empty( $keys ) )
 		return false;
@@ -736,10 +736,8 @@
 	if ( empty( $user_id ) )
 		$user_id = get_current_user_id();
 
-	if ( empty( $blog_id ) ) {
-		global $wpdb;
-		$blog_id = $wpdb->blogid;
-	}
+	if ( empty( $blog_id ) )
+		$blog_id = get_current_blog_id();
 
 	$blogs = get_blogs_of_user( $user_id );
 	if ( is_array( $blogs ) )