diff --git a/wp-blog-header.php b/wp-blog-header.php
index f34d6835bb..378194c4ac 100644
--- a/wp-blog-header.php
+++ b/wp-blog-header.php
@@ -134,8 +134,8 @@ if ( !empty($error) && '404' == $error ) {
 	else $client_etag = false;
 
 	if ( ($client_last_modified && $client_etag) ?
-	    (($client_last_modified == $wp_last_modified) && ($client_etag == $wp_etag)) :
-	    (($client_last_modified == $wp_last_modified) || ($client_etag == $wp_etag)) ) {
+	    ((strtotime($client_last_modified) >= strtotime($wp_last_modified)) && ($client_etag == $wp_etag)) :
+	    ((strtotime($client_last_modified) >= strtotime($wp_last_modified)) || ($client_etag == $wp_etag)) ) {
 		if ( preg_match('/cgi/',php_sapi_name()) ) {
 		    header('Status: 304 Not Modified');
 		    echo "\r\n\r\n";