diff --git a/wstools/c14n.py b/wstools/c14n.py
index de13914..f88160d 100644
--- a/wstools/c14n.py
+++ b/wstools/c14n.py
@@ -55,13 +55,10 @@ 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
 
-_attrs = lambda E: (E.attributes and E.attributes.values()) or []
+import io
+
+_attrs = lambda E: (E.attributes and list(E.attributes.values())) or []
 _children = lambda E: E.childNodes or []
 _IN_XML_NS = lambda n: n.name.startswith("xmlns")
 _inclusive = lambda n: n.unsuppressedPrefixes is None
@@ -69,7 +66,7 @@ _inclusive = lambda n: n.unsuppressedPrefixes is None
 
 # Does a document/PI has lesser/greater document order than the
 # first element?
-_LesserElement, _Element, _GreaterElement = range(3)
+_LesserElement, _Element, _GreaterElement = list(range(3))
 
 
 def _sorter(n1, n2):
@@ -191,7 +188,7 @@ class _implementation:
         canonicalization.'''
 
         # Collect the initial list of xml:foo attributes.
-        xmlattrs = filter(_IN_XML_NS, _attrs(node))
+        xmlattrs = list(filter(_IN_XML_NS, _attrs(node)))
 
         # Walk up and get all xml:XXX attributes we inherit.
         inherited, parent = [], node.parentNode
@@ -367,7 +364,7 @@ class _implementation:
 
             # Create list of NS attributes to render.
             ns_to_render = []
-            for n, v in ns_local.items():
+            for n, v in list(ns_local.items()):
 
                 # If default namespace is XMLNS.BASE or empty,
                 # and if an ancestor was the same
@@ -384,7 +381,7 @@ class _implementation:
 
                 # If not previously rendered
                 # and it's inclusive  or utilized
-                if (n, v) not in ns_rendered.items():
+                if (n, v) not in list(ns_rendered.items()):
                     if inclusive or _utilized(n, node, other_attrs, self.unsuppressedPrefixes):
                         ns_to_render.append((n, v))
                     elif not inclusive:
@@ -400,9 +397,9 @@ class _implementation:
             # Else, add all local and ancestor xml attributes
             # Sort and render the attributes.
             if not inclusive or _in_subset(self.subset, node.parentNode):  # 0426
-                other_attrs.extend(xml_attrs_local.values())
+                other_attrs.extend(list(xml_attrs_local.values()))
             else:
-                other_attrs.extend(xml_attrs.values())
+                other_attrs.extend(list(xml_attrs.values()))
             other_attrs.sort(_sorter)
             for a in other_attrs:
                 self._do_attr(a.nodeName, a.value)
@@ -435,8 +432,8 @@ def Canonicalize(node, output=None, **kw):
                 prefixes that should be inherited.
     '''
     if output:
-        apply(_implementation, (node, output.write), kw)
+        _implementation(*(node, output.write), **kw)
     else:
         s = StringIO.StringIO()
-        apply(_implementation, (node, s.write), kw)
+        _implementation(*(node, s.write), **kw)
         return s.getvalue()