diff --git a/tensor2tensor/data_generators/text_encoder.py b/tensor2tensor/data_generators/text_encoder.py
index b628a538f..f6897d04d 100644
--- a/tensor2tensor/data_generators/text_encoder.py
+++ b/tensor2tensor/data_generators/text_encoder.py
@@ -56,19 +56,13 @@
 _ESCAPE_CHARS = set(u"\\_u;0123456789")
 
 
-def native_to_unicode_py2(s):
-  """Python 2: transform native string to Unicode."""
-  return s if isinstance(s, unicode) else s.decode("utf8")
-
-
-# Conversion between Unicode and UTF-8, if required (on Python2)
 if six.PY2:
-  native_to_unicode = native_to_unicode_py2
-  unicode_to_native = lambda s: s.encode("utf-8")
+  def native_to_unicode(s): return s if isinstance(s, unicode) else s.decode("utf8")  # noqa: F821
+  def unicode_to_native(s): return s.encode("utf-8")
 else:
-  # No conversion required on Python3
-  native_to_unicode = lambda s: s
-  unicode_to_native = lambda s: s
+  # No conversion required on Python >= 3
+  def native_to_unicode(s): return s
+  def unicode_to_native(s): return s
 
 
 class TextEncoder(object):