diff --git a/wsme/tests/test_restjson.py b/wsme/tests/test_restjson.py
index 9935f98..ca80888 100644
--- a/wsme/tests/test_restjson.py
+++ b/wsme/tests/test_restjson.py
@@ -35,7 +35,10 @@ def prepare_value(value, datatype):
     if datatype == decimal.Decimal:
         return str(value)
     if datatype == wsme.types.binary:
-        return base64.encodestring(value).decode('ascii')
+        if six.PY3:
+            return base64.encodebytes(value).decode('ascii')
+        else:
+            return base64.encodestring(value).decode('ascii')
     if datatype == wsme.types.bytes:
         return value.decode('ascii')
     return value
@@ -46,7 +49,10 @@ def prepare_result(value, datatype):
     if value is None:
         return None
     if datatype == wsme.types.binary:
-        return base64.decodestring(value.encode('ascii'))
+        if six.PY3:
+            return base64.decodebytes(value.encode('ascii'))
+        else:
+            return base64.decodestring(value.encode('ascii'))
     if isusertype(datatype):
         datatype = datatype.basetype
     if isinstance(datatype, list):
diff --git a/wsme/tests/test_restxml.py b/wsme/tests/test_restxml.py
index 9e2f08d..50d3d98 100644
--- a/wsme/tests/test_restxml.py
+++ b/wsme/tests/test_restxml.py
@@ -30,7 +30,10 @@ def dumpxml(key, obj, datatype=None):
             node.append(dumpxml('key', item[0], key_type))
             node.append(dumpxml('value', item[1], value_type))
     elif datatype == wsme.types.binary:
-        el.text = base64.encodestring(obj).decode('ascii')
+        if six.PY3:
+            el.text = base64.encodebytes(obj).decode('ascii')
+        else:
+            el.text = base64.encodestring(obj).decode('ascii')
     elif isinstance(obj, wsme.types.bytes):
         el.text = obj.decode('ascii')
     elif isinstance(obj, wsme.types.text):
@@ -96,7 +99,10 @@ def loadxml(el, datatype):
         return d
     else:
         if datatype == wsme.types.binary:
-            return base64.decodestring(el.text.encode('ascii'))
+            if six.PY3:
+                return base64.decodebytes(el.text.encode('ascii'))
+            else:
+                return base64.decodestring(el.text.encode('ascii'))
         if isusertype(datatype):
             datatype = datatype.basetype
         if datatype == datetime.date:
diff --git a/wsme/tests/test_types.py b/wsme/tests/test_types.py
index 4a07130..81e6891 100644
--- a/wsme/tests/test_types.py
+++ b/wsme/tests/test_types.py
@@ -464,13 +464,19 @@ Value: 'v3'. Value should be one of: v., v.",
     def test_binary_to_base(self):
         import base64
         assert types.binary.tobasetype(None) is None
-        expected = base64.encodestring(six.b('abcdef'))
+        if six.PY3:
+            expected = base64.encodebytes(six.b('abcdef'))
+        else:
+            expected = base64.encodestring(six.b('abcdef'))
         assert types.binary.tobasetype(six.b('abcdef')) == expected
 
     def test_binary_from_base(self):
         import base64
         assert types.binary.frombasetype(None) is None
-        encoded = base64.encodestring(six.b('abcdef'))
+        if six.PY3:
+            encoded = base64.encodebytes(six.b('abcdef'))
+        else:
+            encoded = base64.encodestring(six.b('abcdef'))
         assert types.binary.frombasetype(encoded) == six.b('abcdef')
 
     def test_wsattr_weakref_datatype(self):
diff --git a/wsme/types.py b/wsme/types.py
index 0a5fc02..e67f623 100644
--- a/wsme/types.py
+++ b/wsme/types.py
@@ -128,12 +128,18 @@ class BinaryType(UserType):
     def tobasetype(self, value):
         if value is None:
             return None
-        return base64.encodestring(value)
+        if six.PY3:
+            return base64.encodebytes(value)
+        else:
+            return base64.encodestring(value)
 
     def frombasetype(self, value):
         if value is None:
             return None
-        return base64.decodestring(value)
+        if six.PY3:
+            return base64.decodebytes(value)
+        else:
+            return base64.decodestring(value)
 
 
 #: The binary almost-native type