diff --git a/web/lib/timezone.inc.php b/web/lib/timezone.inc.php
index 9fb24331..949f846d 100644
--- a/web/lib/timezone.inc.php
+++ b/web/lib/timezone.inc.php
@@ -42,6 +42,9 @@ function set_tz() {
 
 		if ($result) {
 			$timezone = $result->fetchColumn(0);
+			if (!$timezone) {
+				unset($timezone);
+			}
 		}
 
 		$update_cookie = true;