Index: wp-includes/cache.php
===================================================================
--- wp-includes/cache.php	(revision 21571)
+++ wp-includes/cache.php	(working copy)
@@ -578,7 +578,7 @@
 		echo "</p>";
 		echo '<ul>';
 		foreach ($this->cache as $group => $cache) {
-			echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / 1024, 2 ) . 'k )</li>';
+			echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( print_r( $cache, true ) ) / 1024, 2 ) . 'k )</li>';
 		}
 		echo '</ul>';
 	}