pyderasn.py            | 18 +++++++++---------
 tests/test_crts.py     |  4 ++--
 tests/test_pyderasn.py |  6 +++---

diff --git a/pyderasn.py b/pyderasn.py
index 06bc677bfbfd7cd0705e0844797dd2feb6cb579f03f1e8949cea6a55ef1640a1..b7701ca606516b126e890231960bba47f8f157128e0f5d51f68b0ff234e55d0b 100755
--- a/pyderasn.py
+++ b/pyderasn.py
@@ -269,11 +269,11 @@ for AlgorithmIdentifier of X.509's
 ``tbsCertificate.subjectPublicKeyInfo.algorithm.algorithm``::
 
         (
-            (('parameters',), {
+            (("parameters",), {
                 id_ecPublicKey: ECParameters(),
                 id_GostR3410_2001: GostR34102001PublicKeyParameters(),
             }),
-            (('..', 'subjectPublicKey'), {
+            (("..", "subjectPublicKey"), {
                 id_rsaEncryption: RSAPublicKey(),
                 id_GostR3410_2001: OctetString(),
             }),
@@ -1013,7 +1013,7 @@
 class DecodePathDefBy(object):
     """DEFINED BY representation inside decode path
     """
-    __slots__ = ('defined_by',)
+    __slots__ = ("defined_by",)
 
     def __init__(self, defined_by):
         self.defined_by = defined_by
@@ -1766,12 +1766,12 @@     ::
 
         class KeyUsage(BitString):
             schema = (
-                ('digitalSignature', 0),
-                ('nonRepudiation', 1),
-                ('keyEncipherment', 2),
+                ("digitalSignature", 0),
+                ("nonRepudiation", 1),
+                ("keyEncipherment", 2),
             )
 
-    >>> b = KeyUsage(('keyEncipherment', 'nonRepudiation'))
+    >>> b = KeyUsage(("keyEncipherment", "nonRepudiation"))
     KeyUsage BIT STRING 3 bits nonRepudiation, keyEncipherment
     >>> b.named
     ['nonRepudiation', 'keyEncipherment']
@@ -3228,8 +3228,8 @@     ::
 
         class GeneralName(Choice):
             schema = (
-                ('rfc822Name', IA5String(impl=tag_ctxp(1))),
-                ('dNSName', IA5String(impl=tag_ctxp(2))),
+                ("rfc822Name", IA5String(impl=tag_ctxp(1))),
+                ("dNSName", IA5String(impl=tag_ctxp(2))),
             )
 
     >>> gn = GeneralName()
diff --git a/tests/test_crts.py b/tests/test_crts.py
index 0bf9ffd9b248147c9542c29d871a1a41a2a49fdd62b1ba46b0aa227ee5b524d7..d7e0a44acf34b6821b37a69deab97cdb5eaffcf343a9af7742f8bcf13c2a7eaf 100644
--- a/tests/test_crts.py
+++ b/tests/test_crts.py
@@ -91,8 +91,8 @@
 
 class OrganizationName(Choice):
     schema = (
-        ('printableString', PrintableString()),
-        ('teletexString', TeletexString()),
+        ("printableString", PrintableString()),
+        ("teletexString", TeletexString()),
     )
 
 
diff --git a/tests/test_pyderasn.py b/tests/test_pyderasn.py
index 5200558e35480ffe0a145d1d8f618d01e7a15d7e9122eee758d42a17af6dd39c..2b75df42d57a699cc1be18d5141986e4d6ec9c43294dc807bb837cf874d59e6b 100644
--- a/tests/test_pyderasn.py
+++ b/tests/test_pyderasn.py
@@ -108,11 +108,11 @@ from pyderasn import VideotexString
 from pyderasn import VisibleString
 
 
-settings.register_profile('local', settings(
+settings.register_profile("local", settings(
     deadline=5000,
     perform_health_check=False,
 ))
-settings.load_profile('local')
+settings.load_profile("local")
 LONG_TEST_MAX_EXAMPLES = settings().max_examples * 4
 
 tag_classes = sampled_from((
@@ -2806,7 +2806,7 @@
 
 class UnicodeDecodeErrorMixin(object):
     @given(text(
-        alphabet=''.join(six_unichr(i) for i in list(range(0x0410, 0x044f + 1))),
+        alphabet="".join(six_unichr(i) for i in list(range(0x0410, 0x044f + 1))),
         min_size=1,
         max_size=5,
     ))