--- node.module.orig	2009-06-10 23:01:08.000000000 -0400
+++ node.module	2009-06-10 22:55:20.000000000 -0400
@@ -899,7 +899,7 @@
       }
       if ($weight = (int)variable_get('node_rank_recent', 5)) {
         // Exponential decay with half-life of 6 months, starting at last indexed node
-        $ranking[] = '%d * POW(2, (GREATEST(n.created, n.changed, c.last_comment_timestamp) - %d) * 6.43e-8)';
+        $ranking[] = '%d * POW(2, (GREATEST(n.created, n.changed, c.last_comment_timestamp || 1) - %d) * 6.43e-8)';
         $arguments2[] = $weight;
         $arguments2[] = (int)variable_get('node_cron_last', 0);
         $join2 .= ' INNER JOIN {node} n ON n.nid = i.sid LEFT JOIN {node_comment_statistics} c ON c.nid = i.sid';