Index: wp-admin/options-general.php
===================================================================
--- wp-admin/options-general.php	(revision 10757)
+++ wp-admin/options-general.php	(working copy)
@@ -135,8 +135,8 @@
 $current_offset = get_option('gmt_offset');
 $tzstring = get_option('timezone_string');
 if (empty($tzstring)) { // set the Etc zone if no timezone string exists
-	if ($current_offset < 0) $offnum = ceil($current_offset);
-	else $offnum = floor($current_offset);
+	if ($current_offset < 0) $offnum = - ceil($current_offset);
+	else $offnum = - floor($current_offset);
 	$tzstring = 'Etc/GMT' . (($offnum >= 0) ? '+' : '') . $offnum;
 }
 ?>