diff --git a/nitter.php b/nitter.php
index 77185cb..f5a1eb6 100644
--- a/nitter.php
+++ b/nitter.php
@@ -36,8 +36,8 @@ function nitter_install() {
 function nitter_render(&$a, &$o) {
     // this needs to be a system setting
     $nitter = 'https://nitter.net';
-    if (strstr($o[html],'https://twitter.com')) {
-        $o['html'] = str_replace('https://twitter.com', $nitter, $o[html]);
+    if (strstr($o['html'],'https://twitter.com')) {
+        $o['html'] = str_replace('https://twitter.com', $nitter, $o['html']);
         $o['html'] .= '<hr><p>'.DI::l10n()->t('Links to Twitter in this posting were replaced by links to the Nitter instance at %s', $nitter).'</p>';
     }
 }