diff --git a/.gitignore b/.gitignore
index 732ac9f..7cadb54 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,7 @@
+# Copyright 2023 Datakami
+#
+# SPDX-License-Identifier: MIT
+
 /toggl-api
 /credentials
 /lib/
diff --git a/.reuse/dep5 b/.reuse/dep5
new file mode 100644
index 0000000..822a03c
--- /dev/null
+++ b/.reuse/dep5
@@ -0,0 +1,5 @@
+Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
+
+Files: README.md flake.lock package.json tsconfig.json yarn.lock
+Copyright: 2022 Datakami <hi@datakami.nl>
+License: MIT
diff --git a/.yarnignore b/.yarnignore
index 46bd2dc..6978f59 100644
--- a/.yarnignore
+++ b/.yarnignore
@@ -1,2 +1,6 @@
+# Copyright 2023 Datakami
+#
+# SPDX-License-Identifier: MIT
+
 yarn-cache
 src/*
diff --git a/LICENSES/MIT.txt b/LICENSES/MIT.txt
new file mode 100644
index 0000000..2071b23
--- /dev/null
+++ b/LICENSES/MIT.txt
@@ -0,0 +1,9 @@
+MIT License
+
+Copyright (c) <year> <copyright holders>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/README.md b/README.md
index 15bd2d6..54fda64 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,6 @@
 I use [Amazing Marvin](https://amazingmarvin.com) to track time. This script syncs this to [Toggl](https://toggl.com) and optionally [beeminder](https://beeminder.com).
+
+# Usage:
+```
+$ marvin-timesync 2023-05-01
+```
diff --git a/bin/marvin-timesync.js b/bin/marvin-timesync.js
index 1242da5..3e27753 100755
--- a/bin/marvin-timesync.js
+++ b/bin/marvin-timesync.js
@@ -1,2 +1,7 @@
 #!/usr/bin/env node
+
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 import "../lib/index.js"
diff --git a/flake.nix b/flake.nix
index b19807c..e8583a1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,3 +1,7 @@
+# Copyright 2023 Datakami
+#
+# SPDX-License-Identifier: MIT
+
 {
   inputs.nix-npm-buildpackage.url = "github:serokell/nix-npm-buildpackage";
   inputs.nix-npm-buildpackage.inputs.nixpkgs.follows = "nixpkgs";
diff --git a/src/Beeminder.ts b/src/Beeminder.ts
index f5c81af..e2258f6 100644
--- a/src/Beeminder.ts
+++ b/src/Beeminder.ts
@@ -1,3 +1,7 @@
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 export namespace API {
   export type CreateDatapoint = {
     value: number;
diff --git a/src/Marvin.ts b/src/Marvin.ts
index 5f25339..f87e619 100644
--- a/src/Marvin.ts
+++ b/src/Marvin.ts
@@ -1,3 +1,7 @@
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 import { readFileSync } from "node:fs"
 import { DateTime, Interval, Duration } from "luxon"
 import { inspect } from "node:util"
diff --git a/src/Toggl.ts b/src/Toggl.ts
index 56d5924..052dfd4 100644
--- a/src/Toggl.ts
+++ b/src/Toggl.ts
@@ -1,3 +1,7 @@
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 import { readFileSync } from "node:fs"
 import { Buffer } from "node:buffer"
 import type * as Toggl_types from "./toggl-types.js"
diff --git a/src/index.ts b/src/index.ts
index 65eb41e..88066d1 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,7 @@
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 import { Toggl, Workspace } from "./Toggl.js"
 import { DateTime, Interval, Settings as LuxonSettings } from "luxon"
 import { Marvin } from "./Marvin.js"
diff --git a/src/marvin-types.ts b/src/marvin-types.ts
index 48b370a..3daded7 100644
--- a/src/marvin-types.ts
+++ b/src/marvin-types.ts
@@ -1,3 +1,7 @@
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 export interface Task {
   _id: string;
   createdAt: number;
diff --git a/src/toggl-types.ts b/src/toggl-types.ts
index 0128eb2..a046c39 100644
--- a/src/toggl-types.ts
+++ b/src/toggl-types.ts
@@ -1,3 +1,7 @@
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 namespace models {
   export type CardDetails = unknown;
   export type ContactDetail = unknown;
diff --git a/src/util.ts b/src/util.ts
index 3c247cf..e9b878e 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -1,3 +1,7 @@
+// Copyright 2023 Datakami
+//
+// SPDX-License-Identifier: MIT
+
 import { Duration } from "luxon"
 export namespace DurationUtil {
   export const zero = Duration.fromMillis(0)