diff --git a/program/lib/Roundcube/rcube_washtml.php b/program/lib/Roundcube/rcube_washtml.php
index 0130a4f09..5938d9b87 100644
--- a/program/lib/Roundcube/rcube_washtml.php
+++ b/program/lib/Roundcube/rcube_washtml.php
@@ -505,7 +505,7 @@ class rcube_washtml
         $this->max_nesting_level = (int) @ini_get('xdebug.max_nesting_level');
 
         // SVG need to be parsed as XML
-        $this->is_xml = stripos($html, '<svg') !== false || stripos($html, '<?xml') !== false;
+        $this->is_xml = stripos($html, '<html') === false && stripos($html, '<svg') !== false;
         $method       = $this->is_xml ? 'loadXML' : 'loadHTML';
         $options      = 0;