diff --git a/guessit/rules/common/numeral.py b/guessit/rules/common/numeral.py
index fa698322..35be546d 100644
--- a/guessit/rules/common/numeral.py
+++ b/guessit/rules/common/numeral.py
@@ -36,7 +36,7 @@ def __build_word_numeral(*args):
     :return:
     :rtype:
     """
-    re_ = None
+    re_ = ''
     for word_list in args:
         for word in word_list:
             if not re_: