diff --git a/Parsedown.php b/Parsedown.php
index 3a2803a..59705fd 100755
--- a/Parsedown.php
+++ b/Parsedown.php
@@ -665,7 +665,9 @@ class Parsedown
 
         if (preg_match('/^<(\w*)(?:[ ]*'.$this->regexHtmlAttribute.')*[ ]*(\/)?>/', $Line['text'], $matches))
         {
-            if (in_array($matches[1], $this->textLevelElements))
+            $element = strtolower($matches[1]);
+
+            if (in_array($element, $this->textLevelElements))
             {
                 return;
             }