diff --git a/lark/parser_frontends.py b/lark/parser_frontends.py
index 0ea3138..c4a6f9b 100644
--- a/lark/parser_frontends.py
+++ b/lark/parser_frontends.py
@@ -81,7 +81,7 @@ class Earley_NoLex:
             regexp = t.pattern.to_regexp()
             width = get_regexp_width(regexp)
             if width != (1,1):
-                raise GrammarError('Scanless parsing (lexer=None) requires all tokens to have a width of 1 (terminal %s: %s is %s)' % (sym, regexp, width))
+                raise GrammarError('Scanless parsing (lexer=None) requires all tokens to have a width of 1 (terminal %s: %s is %s)' % (t.name, regexp, width))
             self.regexps[t.name] = re.compile(regexp)
 
     def parse(self, text):
diff --git a/tests/test_trees.py b/tests/test_trees.py
index 6a8866f..2512c3b 100644
--- a/tests/test_trees.py
+++ b/tests/test_trees.py
@@ -1,5 +1,6 @@
 from __future__ import absolute_import
 
+import unittest
 from unittest import TestCase
 import logging
 import copy