diff --git a/api/src/Egw.php b/api/src/Egw.php
index b92785b2e2..2a24e76096 100644
--- a/api/src/Egw.php
+++ b/api/src/Egw.php
@@ -138,6 +138,11 @@ class Egw extends Egw\Base
 				substr($_SERVER['HTTP_X_FORWARDED_URI'], 0, $prefix).
 				$GLOBALS['egw_info']['server']['webserver_url'];
 		}
+		if (isset($_SERVER['HTTP_X_FORWARDED_HOST']) && $GLOBALS['egw_info']['server']['webserver_url'][0] != '/')
+		{
+			$GLOBALS['egw_info']['server']['webserver_url'] = ($_SERVER['HTTPS'] ? 'https://' : 'http://').
+				$_SERVER['HTTP_X_FORWARDED_HOST'].parse_url($GLOBALS['egw_info']['server']['webserver_url'], PHP_URL_PATH);
+		}
 
 		// if no server timezone set, use date_default_timezone_get() to determine it once
 		// it fills to log with deprecated warnings under 5.3 otherwise