diff --git a/backup.php b/backup.php
index 8a2ca441..f9e6c45e 100644
--- a/backup.php
+++ b/backup.php
@@ -72,6 +72,7 @@ if ($_SERVER['REQUEST_METHOD'] == "GET")
 {
    umask (077);
    $path = (ini_get('upload_tmp_dir') != '') ? ini_get('upload_tmp_dir') : '/tmp';
+   date_default_timezone_set(@date_default_timezone_get()); # Suppress date.timezone warnings
    $filename = "postfixadmin-" . date ("Ymd") . "-" . getmypid() . ".sql";
    $backup = $path . DIRECTORY_SEPARATOR . $filename;
 
diff --git a/edit-vacation.php b/edit-vacation.php
index fc3d5058..a35f4210 100644
--- a/edit-vacation.php
+++ b/edit-vacation.php
@@ -55,6 +55,9 @@ else {
    $fUsername = $SESSID_USERNAME;
    $fDomain = $USERID_DOMAIN;
 }
+
+date_default_timezone_set(@date_default_timezone_get()); # Suppress date.timezone warnings
+
 $vh = new VacationHandler($fUsername);
 $vacation_domain = $CONF['vacation_domain'];
 $vacation_goto = preg_replace('/@/', '#', $fUsername);
diff --git a/users/vacation.php b/users/vacation.php
index b4036c35..040ed05c 100644
--- a/users/vacation.php
+++ b/users/vacation.php
@@ -42,6 +42,8 @@ if($CONF['vacation'] == 'NO') {
     exit(0);
 }
 
+date_default_timezone_set(@date_default_timezone_get()); # Suppress date.timezone warnings
+
 $vh = new VacationHandler(authentication_get_username());
 
 if ($_SERVER['REQUEST_METHOD'] == "GET")