1 files changed, 3 insertions, 0 deletions
diff --git a/src/HTML5/Serializer/Traverser.php b/src/HTML5/Serializer/Traverser.php
index bd9d1ce..27a52ff 100644
--- a/src/HTML5/Serializer/Traverser.php
+++ b/src/HTML5/Serializer/Traverser.php
@@ -44,6 +44,9 @@ class Traverser {
     $this->out = $out;
     $this->options = $options;
 
+    if (!isset($this->options['rules'])) {
+      throw new \HTML5\Exception('No Rules specified for output generation.');
+    }
     $rulesClass = $this->options['rules'];
     $this->rules = new $rulesClass($this, $out, $this->options);
   }