diff --git a/filter.php b/filter.php
index a65f8e5..f602609 100644
--- a/filter.php
+++ b/filter.php
@@ -108,6 +108,7 @@ protected function convert_urls_into_codepens(&$text) {
         // <a href="blah">
         $filterignoretagsopen  = ['<a\s[^>]+?>'];
         $filterignoretagsclose = ['</a>'];
+	$ignoretags = [];
         filter_save_ignore_tags($text, $filterignoretagsopen, $filterignoretagsclose, $ignoretags);
 
         static $unicoderegexp;