diff --git a/.flake8 b/.flake8
index e107c2c..96ca3bc 100644
--- a/.flake8
+++ b/.flake8
@@ -5,3 +5,4 @@ select = B,C,E,F,W,B001,B003,B006,B007,B301,B305,B306,B902,Q000,Q001,Q002,Q003
 ignore = E203,E722,W503
 exclude = .tox,build
 max-line-length = 120
+per-file-ignores = coincurve/__init__.py:F401
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b32e236..d4e4e14 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -11,6 +11,7 @@ on:
     - master
 
 env:
+  PYTHON_VERSION_BUILD_EXTRA: '3.9'
   COINCURVE_UPSTREAM_REF: f2d9aeae6d5a7c7fbbba8bbb38b1849b784beef7
   LD_LIBRARY_PATH: ./libsecp256k1_ext/.libs
   DYLD_FALLBACK_LIBRARY_PATH: ./libsecp256k1_ext/.libs
@@ -61,9 +62,9 @@ jobs:
     - name: Run tests
       run: tox -e ${PYTHON_VERSION},bench
 
-    # - name: Lint
-    #   if: startsWith(matrix.os, 'ubuntu-') && matrix.python-version == '3.9' && always()
-    #   run: tox -e lint
+    - name: Lint
+      if: startsWith(matrix.os, 'ubuntu-') && matrix.python-version == env.PYTHON_VERSION_BUILD_EXTRA && always()
+      run: tox -e lint
 
     - name: Upload coverage
       run: codecov -X gcov
@@ -84,7 +85,6 @@ jobs:
     env:
       PYTHON_VERSION: ${{ matrix.python-version }}
       OS_NAME: ${{ matrix.os }}
-      PYTHON_VERSION_BUILD_EXTRA: '3.9'
 
     steps:
     - uses: actions/checkout@v2
diff --git a/_cffi_build/build.py b/_cffi_build/build.py
index ea5c66c..29c9836 100644
--- a/_cffi_build/build.py
+++ b/_cffi_build/build.py
@@ -3,7 +3,6 @@ from collections import namedtuple
 
 from cffi import FFI
 
-
 here = os.path.dirname(os.path.abspath(__file__))
 
 Source = namedtuple('Source', ('h', 'include'))
@@ -23,6 +22,7 @@ def _mk_ffi(sources, name='_libsecp256k1', **kwargs):
 
     return _ffi
 
+
 modules = [
     Source('secp256k1.h', '#include <secp256k1.h>'),
     Source('secp256k1_ecdh.h', '#include <secp256k1_ecdh.h>'),
diff --git a/coincurve/context.py b/coincurve/context.py
index d986c28..b01bd80 100644
--- a/coincurve/context.py
+++ b/coincurve/context.py
@@ -2,6 +2,7 @@ from os import urandom
 from threading import Lock
 
 from coincurve.flags import CONTEXT_ALL, CONTEXT_FLAGS
+
 from ._libsecp256k1 import ffi, lib
 
 
diff --git a/coincurve/ecdsa.py b/coincurve/ecdsa.py
index 1a18a6c..8d14bd0 100644
--- a/coincurve/ecdsa.py
+++ b/coincurve/ecdsa.py
@@ -1,5 +1,6 @@
 from coincurve.context import GLOBAL_CONTEXT
 from coincurve.utils import bytes_to_int, int_to_bytes, sha256
+
 from ._libsecp256k1 import ffi, lib
 
 MAX_SIG_LENGTH = 72
@@ -48,12 +49,12 @@ def serialize_recoverable(recover_sig, context=GLOBAL_CONTEXT):
 
 def deserialize_recoverable(serialized, context=GLOBAL_CONTEXT):
     if len(serialized) != 65:
-        raise ValueError("Serialized signature must be 65 bytes long.")
+        raise ValueError('Serialized signature must be 65 bytes long.')
 
     ser_sig, rec_id = serialized[:64], bytes_to_int(serialized[64:])
 
     if not 0 <= rec_id <= 3:
-        raise ValueError("Invalid recovery id.")
+        raise ValueError('Invalid recovery id.')
 
     recover_sig = ffi.new('secp256k1_ecdsa_recoverable_signature *')
 
@@ -81,7 +82,7 @@ def serialize_compact(raw_sig, context=GLOBAL_CONTEXT):  # no cov
 
 def deserialize_compact(ser_sig, context=GLOBAL_CONTEXT):  # no cov
     if len(ser_sig) != 64:
-        raise Exception("invalid signature length")
+        raise Exception('invalid signature length')
 
     raw_sig = ffi.new('secp256k1_ecdsa_signature *')
     res = lib.secp256k1_ecdsa_signature_parse_compact(context.ctx, raw_sig, ser_sig)
diff --git a/coincurve/keys.py b/coincurve/keys.py
index a42d24b..38ddc6a 100644
--- a/coincurve/keys.py
+++ b/coincurve/keys.py
@@ -14,6 +14,7 @@ from coincurve.utils import (
     sha256,
     validate_secret,
 )
+
 from ._libsecp256k1 import ffi, lib
 
 DEFAULT_NONCE = (ffi.NULL, ffi.NULL)
diff --git a/coincurve/utils.py b/coincurve/utils.py
index 0478f95..d803048 100644
--- a/coincurve/utils.py
+++ b/coincurve/utils.py
@@ -3,6 +3,7 @@ from hashlib import sha256 as _sha256
 from os import urandom
 
 from coincurve.context import GLOBAL_CONTEXT
+
 from ._libsecp256k1 import ffi, lib
 
 GROUP_ORDER = (
diff --git a/pyproject.toml b/pyproject.toml
index 0b6b160..50e14bb 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,3 +23,13 @@ exclude = '''
   | _libsecp256k1\.py$
 )
 '''
+
+[tool.isort]
+default_section = 'THIRDPARTY'
+force_grid_wrap = 0
+include_trailing_comma = true
+known_first_party = 'coincurve'
+line_length = 120
+multi_line_output = 3
+skip_glob = 'setup.py'
+use_parentheses = true
diff --git a/setup.py b/setup.py
index 1caede0..64bb09a 100644
--- a/setup.py
+++ b/setup.py
@@ -25,7 +25,7 @@ except ImportError:
 
 
 sys.path.append(os.path.abspath(os.path.dirname(__file__)))
-from setup_support import absolute, build_flags, detect_dll, has_system_lib
+from setup_support import absolute, build_flags, detect_dll, has_system_lib  # noqa: E402
 
 
 BUILDING_FOR_WINDOWS = detect_dll()
diff --git a/setup_support.py b/setup_support.py
index e5fc1fb..fcd1d9d 100644
--- a/setup_support.py
+++ b/setup_support.py
@@ -1,11 +1,10 @@
 import glob
 import os
 import shutil
+import subprocess
 from contextlib import contextmanager
 from tempfile import mkdtemp
 
-import subprocess
-
 
 @contextmanager
 def workdir():
@@ -42,20 +41,20 @@ def build_flags(library, type_, path):
     """Return separated build flags from pkg-config output"""
 
     pkg_config_path = [path]
-    if "PKG_CONFIG_PATH" in os.environ:
+    if 'PKG_CONFIG_PATH' in os.environ:
         pkg_config_path.append(os.environ['PKG_CONFIG_PATH'])
-    if "LIB_DIR" in os.environ:
+    if 'LIB_DIR' in os.environ:
         pkg_config_path.append(os.environ['LIB_DIR'])
-        pkg_config_path.append(os.path.join(os.environ['LIB_DIR'], "pkgconfig"))
+        pkg_config_path.append(os.path.join(os.environ['LIB_DIR'], 'pkgconfig'))
 
-    options = ["--static", {'I': "--cflags-only-I", 'L': "--libs-only-L", 'l': "--libs-only-l"}[type_]]
+    options = ['--static', {'I': '--cflags-only-I', 'L': '--libs-only-L', 'l': '--libs-only-l'}[type_]]
 
     return [
-        flag.strip("-{}".format(type_))
+        flag.strip('-{}'.format(type_))
         for flag in subprocess.check_output(
-            ["pkg-config"] + options + [library], env=dict(os.environ, PKG_CONFIG_PATH=":".join(pkg_config_path))
+            ['pkg-config'] + options + [library], env=dict(os.environ, PKG_CONFIG_PATH=':'.join(pkg_config_path))
         )
-        .decode("UTF-8")
+        .decode('UTF-8')
         .split()
     ]
 
@@ -68,7 +67,7 @@ def _find_lib():
 
     ffi = FFI()
     try:
-        ffi.dlopen("secp256k1")
+        ffi.dlopen('secp256k1')
         if os.path.exists('/usr/include/secp256k1_ecdh.h'):
             return True
         else:
@@ -76,7 +75,7 @@ def _find_lib():
             return False
     except OSError:
         if 'LIB_DIR' in os.environ:
-            for path in glob.glob(os.path.join(os.environ['LIB_DIR'], "*secp256k1*")):
+            for path in glob.glob(os.path.join(os.environ['LIB_DIR'], '*secp256k1*')):
                 try:
                     FFI().dlopen(path)
                     return True
diff --git a/tests/samples.py b/tests/samples.py
index d71cdb2..20faf0b 100644
--- a/tests/samples.py
+++ b/tests/samples.py
@@ -1,12 +1,12 @@
 PRIVATE_KEY_BYTES = b'\xc2\x8a\x9f\x80s\x8fw\rRx\x03\xa5f\xcfo\xc3\xed\xf6\xce\xa5\x86\xc4\xfcJR#\xa5\xady~\x1a\xc3'
 PRIVATE_KEY_DER = (
-    b"0\x81\x84\x02\x01\x000\x10\x06\x07*\x86H\xce=\x02\x01\x06"
-    b"\x05+\x81\x04\x00\n\x04m0k\x02\x01\x01\x04 \xc2\x8a\x9f"
-    b"\x80s\x8fw\rRx\x03\xa5f\xcfo\xc3\xed\xf6\xce\xa5\x86\xc4"
-    b"\xfcJR#\xa5\xady~\x1a\xc3\xa1D\x03B\x00\x04=\\(u\xc9\xbd"
+    b'0\x81\x84\x02\x01\x000\x10\x06\x07*\x86H\xce=\x02\x01\x06'
+    b'\x05+\x81\x04\x00\n\x04m0k\x02\x01\x01\x04 \xc2\x8a\x9f'
+    b'\x80s\x8fw\rRx\x03\xa5f\xcfo\xc3\xed\xf6\xce\xa5\x86\xc4'
+    b'\xfcJR#\xa5\xady~\x1a\xc3\xa1D\x03B\x00\x04=\\(u\xc9\xbd'
     b"\x11hu\xa7\x1a]\xb6L\xff\xcb\x139k\x16=\x03\x9b\x1d\x93'"
-    b"\x82H\x91\x80C4v\xa45**\xdd\x00\xeb\xb0\xd5\xc9LQ[r\xeb"
-    b"\x10\xf1\xfd\x8f?\x03\xb4/J+%[\xfc\x9a\xa9\xe3"
+    b'\x82H\x91\x80C4v\xa45**\xdd\x00\xeb\xb0\xd5\xc9LQ[r\xeb'
+    b'\x10\xf1\xfd\x8f?\x03\xb4/J+%[\xfc\x9a\xa9\xe3'
 )
 PRIVATE_KEY_HEX = 'c28a9f80738f770d527803a566cf6fc3edf6cea586c4fc4a5223a5ad797e1ac3'
 PRIVATE_KEY_NUM = 87993618360805341115891506172036624893404292644470266399436498750715784469187
@@ -19,9 +19,9 @@ PRIVATE_KEY_PEM = (
 )
 PUBLIC_KEY_COMPRESSED = b"\x03=\\(u\xc9\xbd\x11hu\xa7\x1a]\xb6L\xff\xcb\x139k\x16=\x03\x9b\x1d\x93'\x82H\x91\x80C4"
 PUBLIC_KEY_UNCOMPRESSED = (
-    b"\x04=\\(u\xc9\xbd\x11hu\xa7\x1a]\xb6L\xff\xcb\x139k\x16=\x03"
+    b'\x04=\\(u\xc9\xbd\x11hu\xa7\x1a]\xb6L\xff\xcb\x139k\x16=\x03'
     b"\x9b\x1d\x93'\x82H\x91\x80C4v\xa45**\xdd\x00\xeb\xb0\xd5\xc9"
-    b"LQ[r\xeb\x10\xf1\xfd\x8f?\x03\xb4/J+%[\xfc\x9a\xa9\xe3"
+    b'LQ[r\xeb\x10\xf1\xfd\x8f?\x03\xb4/J+%[\xfc\x9a\xa9\xe3'
 )
 PUBLIC_KEY_X = 27753912938952041417634381842191885283234814940840273460372041880794577257268
 PUBLIC_KEY_Y = 53663045980837260634637807506183816949039230809110041985901491152185762425315
@@ -30,7 +30,7 @@ MESSAGE = (
     b'\xdfw\xeb)\t2R8\xda5\x02\xadE\xdd\xce\xd2\xe0\xb4\xf1\x81\xe7\xdf'
     b':\xce\x82m\xcf\x99\xf3o\x9d\xe6\xfb\xe4\x98O\x88\xcfh\xbe\xfd\xc2'
     b'{\xafm\xb3\xff\xb4QR\xffPu$\xfc>A\'\x03t\xc5\xf9\xd8\xf3I,\xaa"*'
-    b'\xd7q\xfe\xb7]\x11\xa9uB\'d\x89\x03\'3\xb8/\x80\xa2#\x00\xa2\xfe'
+    b"\xd7q\xfe\xb7]\x11\xa9uB'd\x89\x03\'3\xb8/\x80\xa2#\x00\xa2\xfe"
     b'\xff\xae\xb0\x86\xc1/ o\xc8]?\xa05L\xff8\x8az\x92\xc9\xab\x9fg0|'
     b'\\5\x98\xfaG\x9b#\xec\x1a\xc5\x10\xd6\x08\x9c:\x01"\x0c\x812O/i'
     b'\xc4WI\x0c\r\xd8\x81-m1_\x14]$\xf8\x16\xef\x1e\x1d\xb0"Q\x1a\xcf'
@@ -38,13 +38,13 @@ MESSAGE = (
     b'\x84\x1a?No\x10T\xf8\xb8\xd3\x18\xa4\xaf'
 )
 SIGNATURE = (
-    b"0E\x02!\x00\xee$\x1b\x0e@fa\xd4<\x17)\xa7\n\xd0\xd7\xef\x90\xcd\x13"
+    b'0E\x02!\x00\xee$\x1b\x0e@fa\xd4<\x17)\xa7\n\xd0\xd7\xef\x90\xcd\x13'
     b"\xad`\xc1\x06[\xe0\x821\x96\xe29\x80'\x02 \r\x02\x13\xd2\xaf?\x92G"
-    b"\x80&8\x1cVz%2\xb0\x8a\xd0l\x0b4\x9c~\x93\x18\xad\xe4J\x9c-\n"
+    b'\x80&8\x1cVz%2\xb0\x8a\xd0l\x0b4\x9c~\x93\x18\xad\xe4J\x9c-\n'
 )
 RECOVERABLE_SIGNATURE = (
-    b"\xee$\x1b\x0e@fa\xd4<\x17)\xa7\n\xd0\xd7\xef\x90\xcd\x13"
+    b'\xee$\x1b\x0e@fa\xd4<\x17)\xa7\n\xd0\xd7\xef\x90\xcd\x13'
     b"\xad`\xc1\x06[\xe0\x821\x96\xe29\x80'\r\x02\x13\xd2\xaf?"
-    b"\x92G\x80&8\x1cVz%2\xb0\x8a\xd0l\x0b4\x9c~\x93\x18\xad"
-    b"\xe4J\x9c-\n\x00"
+    b'\x92G\x80&8\x1cVz%2\xb0\x8a\xd0l\x0b4\x9c~\x93\x18\xad'
+    b'\xe4J\x9c-\n\x00'
 )
diff --git a/tests/test_bench.py b/tests/test_bench.py
index 05c9db2..1a1095d 100644
--- a/tests/test_bench.py
+++ b/tests/test_bench.py
@@ -1,5 +1,6 @@
 from coincurve import PrivateKey, PublicKey, verify_signature
-from .samples import PRIVATE_KEY_BYTES, PUBLIC_KEY_COMPRESSED, MESSAGE, SIGNATURE
+
+from .samples import MESSAGE, PRIVATE_KEY_BYTES, PUBLIC_KEY_COMPRESSED, SIGNATURE
 
 
 def test_verify_signature_util(benchmark):
diff --git a/tests/test_ecdsa.py b/tests/test_ecdsa.py
index aea05c7..c90a6e5 100644
--- a/tests/test_ecdsa.py
+++ b/tests/test_ecdsa.py
@@ -1,4 +1,5 @@
 from coincurve.ecdsa import cdata_to_der, der_to_cdata
+
 from .samples import SIGNATURE
 
 
diff --git a/tests/test_keys.py b/tests/test_keys.py
index 06a7473..e2a2b76 100644
--- a/tests/test_keys.py
+++ b/tests/test_keys.py
@@ -6,7 +6,9 @@ import pytest
 from coincurve.ecdsa import deserialize_recoverable, recover
 from coincurve.keys import PrivateKey, PublicKey
 from coincurve.utils import bytes_to_int, int_to_bytes_padded, verify_signature
+
 from .samples import (
+    MESSAGE,
     PRIVATE_KEY_BYTES,
     PRIVATE_KEY_DER,
     PRIVATE_KEY_HEX,
@@ -16,12 +18,10 @@ from .samples import (
     PUBLIC_KEY_UNCOMPRESSED,
     PUBLIC_KEY_X,
     PUBLIC_KEY_Y,
-    MESSAGE,
-    SIGNATURE,
     RECOVERABLE_SIGNATURE,
+    SIGNATURE,
 )
 
-
 G = PublicKey(
     b'\x04y\xbef~\xf9\xdc\xbb\xacU\xa0b\x95\xce\x87\x0b\x07\x02\x9b'
     b'\xfc\xdb-\xce(\xd9Y\xf2\x81[\x16\xf8\x17\x98H:\xdaw&\xa3\xc4e'
diff --git a/tests/test_utils.py b/tests/test_utils.py
index c05d6ef..39ba688 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -16,6 +16,7 @@ from coincurve.utils import (
     validate_secret,
     verify_signature,
 )
+
 from .samples import MESSAGE, PRIVATE_KEY_DER, PUBLIC_KEY_COMPRESSED, PUBLIC_KEY_UNCOMPRESSED, SIGNATURE