Index: wp-includes/classes.php
===================================================================
--- wp-includes/classes.php	(revision 15773)
+++ wp-includes/classes.php	(working copy)
@@ -599,7 +599,7 @@
 		$i = 0;
 		foreach ( $meta_query as $q ) {
 			$meta_key = isset( $q['key'] ) ? trim( $q['key'] ) : '';
-			$meta_value = isset( $q['value'] ) ? $q['value'] : '';
+			$meta_value = isset( $q['value'] ) ? maybe_serialize( $q['value'] ) : '';
 			$meta_compare = isset( $q['compare'] ) ? strtoupper( $q['compare'] ) : '=';
 			$meta_type = isset( $q['type'] ) ? strtoupper( $q['type'] ) : 'CHAR';