diff --git a/LICENSE b/LICENSE
index 261eeb9..d9a10c0 100644
--- a/LICENSE
+++ b/LICENSE
@@ -174,28 +174,3 @@
       of your accepting any such warranty or additional liability.
 
    END OF TERMS AND CONDITIONS
-
-   APPENDIX: How to apply the Apache License to your work.
-
-      To apply the Apache License to your work, attach the following
-      boilerplate notice, with the fields enclosed by brackets "[]"
-      replaced with your own identifying information. (Don't include
-      the brackets!)  The text should be enclosed in the appropriate
-      comment syntax for the file format. We also recommend that a
-      file or class name and description of purpose be included on the
-      same "printed page" as the copyright notice for easier
-      identification within third-party archives.
-
-   Copyright [yyyy] [name of copyright owner]
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
diff --git a/README.md b/README.md
index c05413c..e68986d 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,7 @@ from typing import Annotated
 
 from data_enum import DataEnum, UNIQUE, UniqueTogether
 
+
 class Currency(DataEnum):
     __members__ = ("USD", "EUR", "GBP")
 
@@ -34,6 +35,7 @@ class Currency(DataEnum):
     name: str
     code: Annotated[str, UNIQUE]
 
+
 Currency.USD = Currency(symbol="$", name="US Dollar", code="USD")
 Currency.EUR = Currency(symbol="€", name="Euro", code="EUR")
 Currency.GBP = Currency(symbol="£", name="Pound Sterling", code="GBP")
@@ -42,24 +44,24 @@ Currency.GBP = Currency(symbol="£", name="Pound Sterling", code="GBP")
 ### Access data on members
 
 ```py
-Currency.USD.name      # 'US Dollar'
-Currency.EUR.symbol    # '€'
-str(Currency.USD)      # 'USD'
-repr(Currency.USD)     # 'Currency.USD'
+Currency.USD.name  # 'US Dollar'
+Currency.EUR.symbol  # '€'
+str(Currency.USD)  # 'USD'
+repr(Currency.USD)  # 'Currency.USD'
 ```
 
 ### Look up members by name
 
 ```py
-Currency.get("USD")                          # Currency.USD
-Currency.get("MISSING", default=None)        # None
+Currency.get("USD")  # Currency.USD
+Currency.get("MISSING", default=None)  # None
 Currency.get("MISSING", default=Currency.USD)  # Currency.USD
 ```
 
 ### Look up by unique attribute
 
 ```py
-Currency.get(code="EUR")                          # Currency.EUR
+Currency.get(code="EUR")  # Currency.EUR
 Currency.get(code="MISSING", default=Currency.USD)  # Currency.USD
 ```
 
@@ -77,7 +79,7 @@ Currency.USD == Currency.EUR  # False
 Currency.USD == Currency.USD  # True
 
 {Currency.USD, Currency.EUR}  # works in sets
-{Currency.USD: "dollar"}      # works as dict keys
+{Currency.USD: "dollar"}  # works as dict keys
 ```
 
 ### Default values
@@ -93,7 +95,8 @@ class Currency(DataEnum):
     code: Annotated[str, UNIQUE]
     active: bool = True
 
-Currency.USD = Currency(symbol="$", name="US Dollar", code="USD")           # active=True
+
+Currency.USD = Currency(symbol="$", name="US Dollar", code="USD")  # active=True
 Currency.EUR = Currency(symbol="€", name="Euro", code="EUR", active=False)  # active=False
 ```
 
@@ -115,6 +118,7 @@ class State(DataEnum):
     code: Annotated[str, UniqueTogether("location")]
     name: str
 
+
 State.CA_US = State(country="US", code="CA", name="California")
 State.TX_US = State(country="US", code="TX", name="Texas")
 State.ON_CA = State(country="CA", code="ON", name="Ontario")
@@ -146,7 +150,7 @@ DataEnum uses PEP 681 (`@dataclass_transform`) so type checkers (mypy, pyright,
 
 ```py
 Currency(symbol="$", name="US Dollar", code="USD")  # type checker knows these kwargs
-Currency(symbol="$")                                  # type checker flags missing args
+Currency(symbol="$")  # type checker flags missing args
 ```
 
 ### No-data enums
@@ -155,6 +159,7 @@ Currency(symbol="$")                                  # type checker flags missi
 class Direction(DataEnum):
     __members__ = ("NORTH", "SOUTH", "EAST", "WEST")
 
+
 Direction.NORTH = Direction()
 Direction.SOUTH = Direction()
 Direction.EAST = Direction()
@@ -192,6 +197,7 @@ class Color(DataEnum):
     __members__ = ("RED", "BLUE")
     name: str
 
+
 Color.RED = Color(name="Red")
 Color.get("RED")  # raises ConfigurationError (BLUE not yet assigned)
 ```
diff --git a/data_enum/__init__.py b/data_enum/__init__.py
index 29c8f2c..0db7f24 100644
--- a/data_enum/__init__.py
+++ b/data_enum/__init__.py
@@ -1,3 +1,4 @@
+# Copyright (C) 2021 Chase Finch
 """An alternative to the built-in Python `enum` implementation."""
 
 from .data_enum import (
diff --git a/data_enum/_compatibility.py b/data_enum/_compatibility.py
index 3fc9226..952f5b6 100644
--- a/data_enum/_compatibility.py
+++ b/data_enum/_compatibility.py
@@ -1,3 +1,4 @@
+# Copyright (C) 2021 Chase Finch
 """Back-compatibility shims for supported Python versions.
 
 `typing.override` only exists on Python 3.12+, but this package supports
diff --git a/data_enum/data_enum.py b/data_enum/data_enum.py
index c23bee0..9f9bc30 100644
--- a/data_enum/data_enum.py
+++ b/data_enum/data_enum.py
@@ -1,3 +1,4 @@
+# Copyright (C) 2021 Chase Finch
 """An alternative to the built-in Python `enum` implementation."""
 
 from __future__ import annotations
diff --git a/requirements/develop.txt b/requirements/develop.txt
index cf26bdf..8003206 100644
--- a/requirements/develop.txt
+++ b/requirements/develop.txt
@@ -8,6 +8,6 @@ docformatter==1.7.8
 
 wemake-python-styleguide==1.7.0
 
-ruff==0.15.22
+ruff==0.16.0
 
 ty==0.0.61
diff --git a/ruff.toml b/ruff.toml
index ac75644..ef3bf5c 100644
--- a/ruff.toml
+++ b/ruff.toml
@@ -4,6 +4,9 @@ line-length = 99
 target-version = "py313"
 output-format = "grouped"
 
+# The axioms submodule isn't governed by this repo's style
+extend-exclude = ["axioms"]
+
 [lint]
 allowed-confusables = ["\u2018", "\u2019", "\u00d7", "\u2013"]
 select = ["ALL"]
diff --git a/setup.py b/setup.py
index 682d3b3..ac2457a 100644
--- a/setup.py
+++ b/setup.py
@@ -1,3 +1,4 @@
+# Copyright (C) 2021 Chase Finch
 """Define metadata for DataEnum."""
 
 from pathlib import Path
diff --git a/tests/__init__.py b/tests/__init__.py
index 9bae35f..be89eee 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1 +1,2 @@
+# Copyright (C) 2021 Chase Finch
 """Tests for the DataEnum project."""
diff --git a/tests/test_data_enum.py b/tests/test_data_enum.py
index c839e35..0ea7fb0 100644
--- a/tests/test_data_enum.py
+++ b/tests/test_data_enum.py
@@ -1,3 +1,4 @@
+# Copyright (C) 2021 Chase Finch
 """Tests for DataEnum."""
 
 import pickle