diff --git a/htdocs/comm/action/class/actioncomm.class.php b/htdocs/comm/action/class/actioncomm.class.php
index 7d03def1464..5b1f3a6e6f8 100644
--- a/htdocs/comm/action/class/actioncomm.class.php
+++ b/htdocs/comm/action/class/actioncomm.class.php
@@ -2083,8 +2083,8 @@ class ActionComm extends CommonObject
 						}
 
 						if (!empty($conf->global->AGENDA_EXPORT_FIX_TZ)) {
-							$timestampStart = - ($conf->global->AGENDA_EXPORT_FIX_TZ * 3600);
-							$timestampEnd   = - ($conf->global->AGENDA_EXPORT_FIX_TZ * 3600);
+							$timestampStart = $timestampStart - ($conf->global->AGENDA_EXPORT_FIX_TZ * 3600);
+							$timestampEnd   = $timestampEnd - ($conf->global->AGENDA_EXPORT_FIX_TZ * 3600);
 						}
 
 						$urlwithouturlroot = preg_replace('/'.preg_quote(DOL_URL_ROOT, '/').'$/i', '', trim($dolibarr_main_url_root));