Index: wp-includes/plugin.php
===================================================================
--- wp-includes/plugin.php	(revision 12091)
+++ wp-includes/plugin.php	(working copy)
@@ -675,9 +675,12 @@
 	global $wp_filter;
 	static $filter_id_count = 0;
 
-	if ( is_string($function) ) {
+	if ( is_string($function) )
 		return $function;
-	} else if (is_object($function[0]) ) {
+
+	$function = (array) $function;
+
+	if (is_object($function[0]) ) {
 		// Object Class Calling
 		if ( function_exists('spl_object_hash') ) {
 			return spl_object_hash($function[0]) . $function[1];
@@ -692,7 +695,7 @@
 			} else {
 				$obj_idx .= $function[0]->wp_filter_id;
 			}
-	
+
 			return $obj_idx;
 		}
 	} else if ( is_string($function[0]) ) {