diff --git a/libs/parser/grammar.class.php b/libs/parser/grammar.class.php
index <HASH>..<HASH> 100644
--- a/libs/parser/grammar.class.php
+++ b/libs/parser/grammar.class.php
@@ -301,7 +301,8 @@ namespace org\octris\core\parser {
             if (!is_null($this->initial)) {
                 $valid = $v($this->rules[$this->initial]);
             } else {
-                die("TODO: no initial rule\n");
+                // no initial rule, build one
+                $valid = $v(['$alternation' => array_keys($this->rules)]);
             }
 
             $expected = array_unique($expected);
build an "alternation" rule including all defined rules if no initial rule is defined