diff -r 1ab7bcd4e176 Lib/collections/__init__.py
--- a/Lib/collections/__init__.py	Wed Dec 30 21:41:53 2015 +0200
+++ b/Lib/collections/__init__.py	Wed Dec 30 22:03:34 2015 +0200
@@ -410,12 +410,13 @@ def namedtuple(typename, field_names, ve
             raise ValueError('Encountered duplicate field name: %r' % name)
         seen.add(name)
 
+    field_names = tuple(map(_sys.intern, field_names))
     # Fill-in the class template
     class_definition = _class_template.format(
         typename = typename,
-        field_names = tuple(field_names),
+        field_names = field_names,
         num_fields = len(field_names),
-        arg_list = repr(tuple(field_names)).replace("'", "")[1:-1],
+        arg_list = repr(field_names).replace("'", "")[1:-1],
         repr_fmt = ', '.join(_repr_template.format(name=name)
                              for name in field_names),
         field_defs = '\n'.join(_field_template.format(index=index, name=name)