diff --git a/IPython/core/formatters.py b/IPython/core/formatters.py
index d441d68..9f5ded5 100644
--- a/IPython/core/formatters.py
+++ b/IPython/core/formatters.py
@@ -15,6 +15,7 @@ import json
 import sys
 import traceback
 import warnings
+from io import StringIO
 
 from decorator import decorator
 
@@ -655,11 +656,7 @@ class PlainTextFormatter(BaseFormatter):
         if not self.pprint:
             return repr(obj)
         else:
-            # handle str and unicode on Python 2
-            # io.StringIO only accepts unicode,
-            # cStringIO doesn't handle unicode on py2,
-            # StringIO allows str, unicode but only ascii str
-            stream = pretty.CUnicodeIO()
+            stream = StringIO()
             printer = pretty.RepresentationPrinter(stream, self.verbose,
                 self.max_width, self.newline,
                 max_seq_length=self.max_seq_length,
diff --git a/IPython/lib/pretty.py b/IPython/lib/pretty.py
index 4c18089..155dfee 100644
--- a/IPython/lib/pretty.py
+++ b/IPython/lib/pretty.py
@@ -83,12 +83,11 @@ import types
 import re
 import datetime
 from collections import deque
+from io import StringIO
 
 from IPython.utils.py3compat import PYPY, cast_unicode
 from IPython.utils.encoding import get_stream_enc
 
-from io import StringIO
-
 
 __all__ = ['pretty', 'pprint', 'PrettyPrinter', 'RepresentationPrinter',
     'for_type', 'for_type_by_name']
@@ -114,7 +113,7 @@ def pretty(obj, verbose=False, max_width=79, newline='\n', max_seq_length=MAX_SE
     """
     Pretty print the object's representation.
     """
-    stream = CUnicodeIO()
+    stream = StringIO()
     printer = RepresentationPrinter(stream, verbose, max_width, newline, max_seq_length=max_seq_length)
     printer.pretty(obj)
     printer.flush()