Index: wp-content/plugins/akismet/akismet.php
===================================================================
--- wp-content/plugins/akismet/akismet.php	(revision 111740)
+++ wp-content/plugins/akismet/akismet.php	(working copy)
@@ -263,7 +263,7 @@
 
 		$post = get_post( $comment['comment_post_ID'] );
 		$last_updated = strtotime( $post->post_modified_gmt );
-		$diff = time() - $last_updated;
+		$diff = strtotime(gmdate("Y-m-d H:i:s")) - $last_updated;
 		$diff = $diff / 86400;
 
 		if ( $post->post_type == 'post' && $diff > 30 && get_option( 'akismet_discard_month' ) == 'true' )