diff --git a/docs/source/conf.py b/docs/source/conf.py
index 6cc41bed..7fd1b4f1 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 #
 # Configuration file for the Sphinx documentation builder.
 #
diff --git a/src/wily/__main__.py b/src/wily/__main__.py
index d89f8a0c..e83be651 100644
--- a/src/wily/__main__.py
+++ b/src/wily/__main__.py
@@ -1,4 +1,3 @@
-# -*- coding: UTF-8 -*-
 """Main command line."""
 
 import click
diff --git a/src/wily/archivers/__init__.py b/src/wily/archivers/__init__.py
index e440c6de..833de7c1 100644
--- a/src/wily/archivers/__init__.py
+++ b/src/wily/archivers/__init__.py
@@ -25,7 +25,7 @@ class Revision:
     deleted_files: List[str]
 
 
-class BaseArchiver(object):
+class BaseArchiver:
     """Abstract Archiver Class."""
 
     def revisions(self, path: str, max_revisions: int) -> List[Revision]:
diff --git a/src/wily/cache.py b/src/wily/cache.py
index bf11593f..6206eda3 100644
--- a/src/wily/cache.py
+++ b/src/wily/cache.py
@@ -35,7 +35,7 @@ def exists(config):
         return False
     index_path = pathlib.Path(config.cache_path) / "index.json"
     if index_path.exists():
-        with open(index_path, "r") as out:
+        with open(index_path) as out:
             index = json.load(out)
         if index["version"] != __version__:
             # TODO: Inspect the versions properly.
@@ -216,7 +216,7 @@ def get_default_metrics(config):
             o = resolve_operator(operator)
             if o.cls.default_metric_index is not None:
                 metric = o.cls.metrics[o.cls.default_metric_index]
-                default_metrics.append("{0}.{1}".format(o.cls.name, metric.name))
+                default_metrics.append(f"{o.cls.name}.{metric.name}")
     return default_metrics
 
 
diff --git a/src/wily/commands/diff.py b/src/wily/commands/diff.py
index 4798acb3..77815d64 100644
--- a/src/wily/commands/diff.py
+++ b/src/wily/commands/diff.py
@@ -145,12 +145,12 @@ def diff(config, files, metrics, changes_only=True, detail=True, revision=None):
                         )
                     )
                 else:
-                    metrics_data.append("{0:n} -> {1:n}".format(current, new))
+                    metrics_data.append(f"{current:n} -> {new:n}")
             else:
                 if current == "-" and new == "-":
                     metrics_data.append("-")
                 else:
-                    metrics_data.append("{0} -> {1}".format(current, new))
+                    metrics_data.append(f"{current} -> {new}")
         if has_changes or not changes_only:
             results.append((file, *metrics_data))
         else:
diff --git a/src/wily/config.py b/src/wily/config.py
index f838ee6c..9de1aa1b 100644
--- a/src/wily/config.py
+++ b/src/wily/config.py
@@ -39,7 +39,7 @@ def generate_cache_path(path):
 
 
 @dataclass
-class WilyConfig(object):
+class WilyConfig:
     """
     Wily configuration.
 
diff --git a/src/wily/lang.py b/src/wily/lang.py
index 38828db3..d5625b77 100644
--- a/src/wily/lang.py
+++ b/src/wily/lang.py
@@ -1,5 +1,4 @@
 """Language/i18n support for the CLI."""
-# -*- coding: UTF-8 -*-
 
 import gettext
 import os
diff --git a/src/wily/operators/__init__.py b/src/wily/operators/__init__.py
index 2c0737b5..88a3d659 100644
--- a/src/wily/operators/__init__.py
+++ b/src/wily/operators/__init__.py
@@ -37,7 +37,7 @@ class OperatorLevel(Enum):
     Object = 2
 
 
-class BaseOperator(object):
+class BaseOperator:
     """Abstract Operator Class."""
 
     """Name of the operator."""
diff --git a/src/wily/state.py b/src/wily/state.py
index 9bb38ee2..cfa34417 100644
--- a/src/wily/state.py
+++ b/src/wily/state.py
@@ -14,7 +14,7 @@
 
 
 @dataclass
-class IndexedRevision(object):
+class IndexedRevision:
     """Union of revision and the operators executed."""
 
     revision: Revision
@@ -108,7 +108,7 @@ def store(self, config, archiver, stats):
         return cache.store(config, archiver, self.revision, stats)
 
 
-class Index(object):
+class Index:
     """The index of the wily cache."""
 
     operators = None
@@ -206,7 +206,7 @@ def save(self):
         cache.store_archiver_index(self.config, self.archiver, data)
 
 
-class State(object):
+class State:
     """
     The wily process state.
 
diff --git a/test/integration/test_build.py b/test/integration/test_build.py
index 368d4d19..e24a5abd 100644
--- a/test/integration/test_build.py
+++ b/test/integration/test_build.py
@@ -11,7 +11,7 @@
 import pytest
 from click.testing import CliRunner
 from git import Repo, Actor
-from mock import patch
+from unittest.mock import patch
 
 import wily.__main__ as main
 from wily.archivers import ALL_ARCHIVERS
diff --git a/test/integration/test_graph.py b/test/integration/test_graph.py
index e584ff64..2ab6015c 100644
--- a/test/integration/test_graph.py
+++ b/test/integration/test_graph.py
@@ -1,5 +1,5 @@
 import sys
-from mock import patch
+from unittest.mock import patch
 import tempfile
 from click.testing import CliRunner
 
diff --git a/test/unit/test_archivers.py b/test/unit/test_archivers.py
index b9927f69..51655d3e 100644
--- a/test/unit/test_archivers.py
+++ b/test/unit/test_archivers.py
@@ -1,19 +1,19 @@
 import pathlib
 
 import pytest
-from mock import patch
+from unittest.mock import patch
 
 import wily.archivers
 import wily.archivers.git as git
 import wily.config
 
 
-class MockAuthor(object):
+class MockAuthor:
     name = "Mr Test"
     email = "test@test.com"
 
 
-class MockStats(object):
+class MockStats:
     files = {}
 
 
@@ -21,7 +21,7 @@ class MockStats(object):
 TEST_STATS = MockStats()
 
 
-class MockCommit(object):
+class MockCommit:
     name_rev = "1234 bbb"
     author = TEST_AUTHOR
     committed_date = "1/1/1990"
@@ -33,11 +33,11 @@ def __init__(self, message):
         self.message = message
 
 
-class MockHead(object):
+class MockHead:
     is_detached = False
 
 
-class MockRepo(object):
+class MockRepo:
     active_branch = "master"
     bare = False
     _is_dirty = False
diff --git a/test/unit/test_build_unit.py b/test/unit/test_build_unit.py
index c7e76561..5f2fdbc2 100644
--- a/test/unit/test_build_unit.py
+++ b/test/unit/test_build_unit.py
@@ -1,5 +1,5 @@
 import pytest
-from mock import patch
+from unittest.mock import patch
 
 import wily.commands.build as build
 from wily.config import DEFAULT_CONFIG
diff --git a/test/unit/test_cli.py b/test/unit/test_cli.py
index f6957c1c..b952f656 100644
--- a/test/unit/test_cli.py
+++ b/test/unit/test_cli.py
@@ -1,7 +1,7 @@
 import pytest
 
 from click.testing import CliRunner
-from mock import patch
+from unittest.mock import patch
 from pathlib import Path
 
 import wily.__main__ as main
diff --git a/test/unit/test_cyclomatic.py b/test/unit/test_cyclomatic.py
index a40e23ef..dab50b31 100644
--- a/test/unit/test_cyclomatic.py
+++ b/test/unit/test_cyclomatic.py
@@ -1,12 +1,12 @@
 """
 Tests for the cyclomatic complexity operator's ability to handle bad data from radon.
 """
-import mock
+from unittest import mock
 import wily.operators.cyclomatic
 from wily.config import DEFAULT_CONFIG
 
 
-class MockCC(object):
+class MockCC:
     results = {}