diff --git a/thriftpy2/_compat.py b/thriftpy2/_compat.py
index 84d77c9..c886e35 100644
--- a/thriftpy2/_compat.py
+++ b/thriftpy2/_compat.py
@@ -11,11 +11,9 @@
 
 import platform
 import sys
-from urllib.parse import urlparse
-from urllib.request import urlopen
+from urllib.parse import urlparse  # noqa
+from urllib.request import urlopen  # noqa
 
-PY3 = sys.version_info[0] == 3
-PY35 = sys.version_info >= (3, 5)
 PYPY = "__pypy__" in sys.modules
 
 UNIX = platform.system() in ("Linux", "Darwin")
diff --git a/thriftpy2/parser/parser.py b/thriftpy2/parser/parser.py
index 5948d0f..d20081d 100644
--- a/thriftpy2/parser/parser.py
+++ b/thriftpy2/parser/parser.py
@@ -9,16 +9,15 @@
 
 import collections
 import os
-import sys
 import types
+
 from ply import lex, yacc
-from .lexer import *  # noqa
-from .exc import ThriftParserError, ThriftGrammarError
-from thriftpy2._compat import urlopen, urlparse, PY3
-from ..thrift import gen_init, TType, TPayload, TException
 
-if not PY3:
-    from io import open
+from thriftpy2._compat import urlopen, urlparse
+
+from ..thrift import TException, TPayload, TType, gen_init
+from .exc import ThriftGrammarError, ThriftParserError
+from .lexer import *  # noqa
 
 
 def p_error(p):
@@ -582,11 +581,8 @@ def parse(path, module_name=None, include_dirs=None, include_dir=None,
                                 'with path in protocol \'{}\''.format(
                                     url_scheme))
 
-    if PY3:
-        if isinstance(data, bytes):
-            data = data.decode(encoding)
-    else:
-        data = data.encode(encoding)
+    if isinstance(data, bytes):
+        data = data.decode(encoding)
 
     if module_name is not None and not module_name.endswith('_thrift'):
         raise ThriftParserError('thriftpy2 can only generate module with '
diff --git a/thriftpy2/protocol/compact.py b/thriftpy2/protocol/compact.py
index 0481119..8823236 100644
--- a/thriftpy2/protocol/compact.py
+++ b/thriftpy2/protocol/compact.py
@@ -8,12 +8,9 @@
 
 import six
 
-from .exc import TProtocolException
+from ..thrift import TException, TType
 from .base import TProtocolBase
-from ..thrift import TException
-from ..thrift import TType
-
-from thriftpy2._compat import PY3
+from .exc import TProtocolException
 
 CLEAR = 0
 FIELD_WRITE = 1
@@ -66,10 +63,7 @@ def write_varint(trans, n):
             n = n >> 7
     data = array.array('B', out)
 
-    if PY3:
-        trans.write(data.tobytes())
-    else:
-        trans.write(data.tostring())
+    trans.write(data.tobytes())
 
 
 def read_varint(trans):
diff --git a/thriftpy2/rpc.py b/thriftpy2/rpc.py
index c9e7664..ab6d567 100644
--- a/thriftpy2/rpc.py
+++ b/thriftpy2/rpc.py
@@ -7,7 +7,8 @@
 import urllib
 import warnings
 
-from thriftpy2._compat import PY35
+from thriftpy2.contrib.aio.rpc import make_client as make_aio_client  # noqa
+from thriftpy2.contrib.aio.rpc import make_server as make_aio_server  # noqa
 from thriftpy2.protocol import TBinaryProtocolFactory
 from thriftpy2.server import TThreadedServer
 from thriftpy2.thrift import TClient, TProcessor
@@ -122,9 +123,3 @@ def client_context(service, host="localhost", port=9090, unix_socket=None,
 
     finally:
         transport.close()
-
-
-if PY35:
-    from thriftpy2.contrib.aio.rpc import make_client as make_aio_client
-    from thriftpy2.contrib.aio.rpc import \
-        make_server as make_aio_server  # noqa
diff --git a/thriftpy2/thrift.py b/thriftpy2/thrift.py
index 30cc517..6454ea5 100644
--- a/thriftpy2/thrift.py
+++ b/thriftpy2/thrift.py
@@ -12,12 +12,9 @@
 import functools
 import linecache
 import types
+from itertools import zip_longest
 
-from ._compat import with_metaclass, PY3
-if PY3:
-    from itertools import zip_longest
-else:
-    from itertools import izip_longest as zip_longest
+from ._compat import with_metaclass
 
 
 def args_to_kwargs(thrift_spec, *args, **kwargs):