diff --git a/LICENSE b/LICENSE
index 6efa3e6..f4dd167 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,7 +1,7 @@
 MIT License
 
-Copyright (c) 2025 Will Riley
-Copyright (c) 2026 Jan Kowalleck — modifications and maintenance.
+Copyright (c) 2025 Will Riley - original author
+Copyright (c) 2026 Jan Kowalleck - modifications and maintenance
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/src/rfc3987_syntax2/__init__.py b/src/rfc3987_syntax2/__init__.py
index c1f81aa..7300822 100644
--- a/src/rfc3987_syntax2/__init__.py
+++ b/src/rfc3987_syntax2/__init__.py
@@ -1 +1,5 @@
+# Copyright (c) 2025 Will Riley - original author
+# Copyright (c) 2026 Jan Kowalleck - modifications and maintenance
+# SPDX-License-Identifier: MIT
+
 from .syntax_helpers import *
diff --git a/src/rfc3987_syntax2/syntax_helpers.py b/src/rfc3987_syntax2/syntax_helpers.py
index 25830e7..7b8adc6 100644
--- a/src/rfc3987_syntax2/syntax_helpers.py
+++ b/src/rfc3987_syntax2/syntax_helpers.py
@@ -1,3 +1,7 @@
+# Copyright (c) 2025 Will Riley - original author
+# Copyright (c) 2026 Jan Kowalleck - modifications and maintenance
+# SPDX-License-Identifier: MIT
+
 from typing import Callable
 
 from lark import Lark, ParseTree, exceptions
diff --git a/src/rfc3987_syntax2/syntax_rfc3987.lark b/src/rfc3987_syntax2/syntax_rfc3987.lark
index f0811e9..101b293 100644
--- a/src/rfc3987_syntax2/syntax_rfc3987.lark
+++ b/src/rfc3987_syntax2/syntax_rfc3987.lark
@@ -1,3 +1,6 @@
+// Copyright (c) 2025 Will Riley - original author
+// Copyright (c) 2026 Jan Kowalleck - modifications and maintenance
+// SPDX-License-Identifier: MIT
 
 iri: scheme ":" ihier_part ("?" iquery)? ("#" ifragment)?
 
diff --git a/src/rfc3987_syntax2/utils.py b/src/rfc3987_syntax2/utils.py
index af16a5d..32f05dc 100644
--- a/src/rfc3987_syntax2/utils.py
+++ b/src/rfc3987_syntax2/utils.py
@@ -1,3 +1,7 @@
+# Copyright (c) 2025 Will Riley - original author
+# Copyright (c) 2026 Jan Kowalleck - modifications and maintenance
+# SPDX-License-Identifier: MIT
+
 from pathlib import Path
 
 
diff --git a/tests/__init__.py b/tests/__init__.py
index 4585dbd..13df859 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1,3 +1,7 @@
+# Copyright (c) 2025 Will Riley - original author
+# Copyright (c) 2026 Jan Kowalleck - modifications and maintenance
+# SPDX-License-Identifier: MIT
+
 import json
 from pathlib import Path
 from typing import TypedDict
diff --git a/tests/test_syntax.py b/tests/test_syntax.py
index 4262b88..c096cc1 100644
--- a/tests/test_syntax.py
+++ b/tests/test_syntax.py
@@ -1,3 +1,7 @@
+# Copyright (c) 2025 Will Riley - original author
+# Copyright (c) 2026 Jan Kowalleck - modifications and maintenance
+# SPDX-License-Identifier: MIT
+
 from typing import TYPE_CHECKING
 
 import pytest