diff --git a/lib/htmloutputter.php b/lib/htmloutputter.php
index 8f3b1a609c..5da1fbe148 100644
--- a/lib/htmloutputter.php
+++ b/lib/htmloutputter.php
@@ -113,9 +113,7 @@ class HTMLOutputter extends XMLOutputter
             // Browsers don't like it when <?xml it output for non-xhtml documents
             $this->xw->startDocument('1.0', 'UTF-8');
         }
-        if ($doc) {
-            $this->xw->writeDTD('html', $public, $system);
-        }
+        $this->xw->writeDTD('html', $public, $system);
 
         $language = $this->getLanguage();