diff --git a/src/unparsed-blocks/ATXHeading.php b/src/unparsed-blocks/ATXHeading.php
index f42112c..7bba617 100644
--- a/src/unparsed-blocks/ATXHeading.php
+++ b/src/unparsed-blocks/ATXHeading.php
@@ -30,7 +30,8 @@ public static function consume(
 
     list($first, $rest) = $lines->getFirstLineAndRest();
 
-    $title = $level = null;
+    $title = null;
+    $level = null;
     foreach ($patterns as $pattern) {
       $matches = Regex\first_match($first, $pattern);
       if ($matches is nonnull) {