diff --git a/pysimplesoap/c14n.py b/pysimplesoap/c14n.py

index 5749e49..6effd0c 100644

--- a/pysimplesoap/c14n.py

+++ b/pysimplesoap/c14n.py

@@ -55,11 +55,7 @@ except:

     class XMLNS:

         BASE = "http://www.w3.org/2000/xmlns/"

         XML = "http://www.w3.org/XML/1998/namespace"

-try:

-    import cStringIO

-    StringIO = cStringIO

-except ImportError:

-    import StringIO

+import io

 _attrs = lambda E: (E.attributes and E.attributes.values()) or []

 _children = lambda E: E.childNodes or []

@@ -428,6 +424,6 @@ def Canonicalize(node, output=None, **kw):

     if output:

         apply(_implementation, (node, output.write), kw)

     else:

-        s = StringIO.StringIO()

+        s = io.StringIO()

         apply(_implementation, (node, s.write), kw)

         return s.getvalue()

diff --git a/pysimplesoap/transport.py b/pysimplesoap/transport.py

index 8e541d1..45ef8d9 100644

--- a/pysimplesoap/transport.py

+++ b/pysimplesoap/transport.py

@@ -166,13 +166,7 @@ try:

 except ImportError:

     pass

 else:

-    try:

-        from cStringIO import StringIO

-    except ImportError:

-        try:

-            from StringIO import StringIO

-        except ImportError:

-            from io import StringIO

+    from io import StringIO

     class pycurlTransport(TransportBase):

         _wrapper_version = pycurl.version

diff --git a/pysimplesoap/xmlsec.py b/pysimplesoap/xmlsec.py

index 2f96df7..053149f 100644

--- a/pysimplesoap/xmlsec.py

+++ b/pysimplesoap/xmlsec.py

@@ -15,7 +15,7 @@ from __future__ import print_function

 import base64

 import hashlib

 import os

-from cStringIO import StringIO

+from io import StringIO

 from M2Crypto import BIO, EVP, RSA, X509, m2

 # if lxml is not installed, use c14n.py native implementation