pygost/asn1schemas/x509.py | 4 ++--
 pygost/gost34112012256.py  | 4 ++--
 pygost/gost34112012512.py  | 4 ++--
 pygost/gost3413.py         | 6 +++---
 pygost/pbkdf2.py           | 2 +-
 pygost/test_pfx.py         | 4 ++--
 setup.py                   | 2 +-

diff --git a/pygost/asn1schemas/x509.py b/pygost/asn1schemas/x509.py
index 8b547bc4fc81bd409f3bff893c645ad85cb4735ba2a640818180469ed6fda7d3..aecf8d8dc0bc6adb1c9d9a284c87d9a028c50810bcf0e9194396100ef489fdd1 100644
--- a/pygost/asn1schemas/x509.py
+++ b/pygost/asn1schemas/x509.py
@@ -140,8 +140,8 @@
 
 class BasicConstraints(Sequence):
     schema = (
-        ('cA', Boolean(default=False)),
-        # ('pathLenConstraint', PathLenConstraint(optional=True)),
+        ("cA", Boolean(default=False)),
+        # ("pathLenConstraint", PathLenConstraint(optional=True)),
     )
 
 
diff --git a/pygost/gost34112012256.py b/pygost/gost34112012256.py
index 8896da90435ed4ad523a6a16867bc077174d62e824ea7e387d4ab128bd3252b3..35ac2c7207b3767bc26e490f61e348593bc2174f038be636db837c7573c332ca 100644
--- a/pygost/gost34112012256.py
+++ b/pygost/gost34112012256.py
@@ -8,9 +8,9 @@ from pygost.gost34112012 import GOST34112012
 
 
 class GOST34112012256(GOST34112012):
-    def __init__(self, data=b''):
+    def __init__(self, data=b""):
         super(GOST34112012256, self).__init__(data, digest_size=32)
 
 
-def new(data=b''):
+def new(data=b""):
     return GOST34112012256(data)
diff --git a/pygost/gost34112012512.py b/pygost/gost34112012512.py
index eaa58ef3c46b7cab5ccd74585ab025030b3d349ca875c80b391425f93cff0d56..2c263979996bc18874479266c4917bf516baaee715fbb6ea2d284df9519bf0e4 100644
--- a/pygost/gost34112012512.py
+++ b/pygost/gost34112012512.py
@@ -9,11 +9,11 @@ from pygost.pbkdf2 import pbkdf2 as pbkdf2_base
 
 
 class GOST34112012512(GOST34112012):
-    def __init__(self, data=b''):
+    def __init__(self, data=b""):
         super(GOST34112012512, self).__init__(data, digest_size=64)
 
 
-def new(data=b''):
+def new(data=b""):
     return GOST34112012512(data)
 
 
diff --git a/pygost/gost3413.py b/pygost/gost3413.py
index 781d3943c0d1ff206d4409e82b5637f64c583c4d8c83dd81ab2217b73516373c..321d0ef0c0328c971cbf0e4bd2bd834c962e778835ede2364d71584d7ff86a3a 100644
--- a/pygost/gost3413.py
+++ b/pygost/gost3413.py
@@ -274,7 +274,7 @@
 
 def _mac_ks(encrypter, bs):
     Rb = Rb128 if bs == 16 else Rb64
-    _l = encrypter(bs * b'\x00')
+    _l = encrypter(bs * b"\x00")
     k1 = _mac_shift(bs, _l, Rb) if bytearray(_l)[0] & 0x80 > 0 else _mac_shift(bs, _l)
     k2 = _mac_shift(bs, k1, Rb) if bytearray(k1)[0] & 0x80 > 0 else _mac_shift(bs, k1)
     return k1, k2
@@ -294,7 +294,7 @@     if len(data) % bs == 0:
         tail_offset = len(data) - bs
     else:
         tail_offset = len(data) - (len(data) % bs)
-    prev = bs * b'\x00'
+    prev = bs * b"\x00"
     for i in xrange(0, tail_offset, bs):
         prev = encrypter(strxor(data[i:i + bs], prev))
     tail = data[tail_offset:]
@@ -337,7 +337,7 @@     if len(data) % bs == 0:
         tail_offset = len(data) - bs
     else:
         tail_offset = len(data) - (len(data) % bs)
-    prev = bs * b'\x00'
+    prev = bs * b"\x00"
     sections = len(data) // section_size
     if len(data) % section_size != 0:
         sections += 1
diff --git a/pygost/pbkdf2.py b/pygost/pbkdf2.py
index cd9da39d98b6c9a5f112e7e053c25580ab7c88167b92b7597e9dfe34168faa75..8fc1501d10f4061d8c40195c3c01be1759c4131397f61c923ec51b626fe156bf 100644
--- a/pygost/pbkdf2.py
+++ b/pygost/pbkdf2.py
@@ -28,7 +28,7 @@         icpy.update(msg)
         ocpy.update(icpy.digest())
         return ocpy.digest()
 
-    dkey = b''
+    dkey = b""
     loop = 1
     while len(dkey) < dklen:
         prev = prf(salt + long2bytes(loop, 4))
diff --git a/pygost/test_pfx.py b/pygost/test_pfx.py
index 66a798a6e540dd8e78c8a5326892b4d2c67320864d61ef0a545e09b45b8218a1..52b72dbc8b8f21164a2a6fca33c3b64eb168fb4467a3d5120f762799bdb23158 100644
--- a/pygost/test_pfx.py
+++ b/pygost/test_pfx.py
@@ -72,7 +72,7 @@ AwcBAQIDBEAIFX0fyZe20QKKhWm6WYX+S92Gt6zaXroXOvAmayzLfZ5Sd9C2t9zZ
 JSg6M8RBUYpw/8ym5ou1o2nDa09M5zF3BCCpzyCQBI+rzfISeKvPV1ROfcXiYU93
 mwcl1xQV2G5/fgICB9A=
     """)
-    password = u'Пароль для PFX'
+    password = u"Пароль для PFX"
 
     def test_shrouded_key_bag(self):
         private_key_info_expected = b64decode(b"""
@@ -162,7 +162,7 @@         self.assertSequenceEqual(tail, b"")
         _, outer_safe_contents = pfx["authSafe"]["content"].defined
         mac_data = pfx["macData"]
         mac_key = gost34112012_pbkdf2(
-            password=self.password.encode('utf-8'),
+            password=self.password.encode("utf-8"),
             salt=bytes(mac_data["macSalt"]),
             iterations=int(mac_data["iterations"]),
             dklen=96,
diff --git a/setup.py b/setup.py
index d85af47f1a59d41284e15870c2b5168345d9397be244123c40e081e3a9e72401..7d375d0b410915f85fa646c233879354fb58cf1fcd0651c65d0e830b1cf1039b 100644
--- a/setup.py
+++ b/setup.py
@@ -27,7 +27,7 @@     package_data={
         "pygost": ["stubs/**/*.pyi"],
     },
     data_files=(
-        ('', (
+        ("", (
             "AUTHORS",
             "COPYING",
             "FAQ",