diff --git a/@xen-orchestra/defined/.USAGE.md b/@xen-orchestra/defined/.USAGE.md
index e69de29bb2d..bc71fccad85 100644
--- a/@xen-orchestra/defined/.USAGE.md
+++ b/@xen-orchestra/defined/.USAGE.md
@@ -0,0 +1,29 @@
+### `defined()`
+
+Returns the first non-`undefined` value from a list of arguments, evaluating functions if needed.
+
+There is two ways to use this function:
+
+- either with a single array argument: it should return the first non-undefined item
+- or with multiple arguments: it should return the first non-undefined argument
+
+If only `undefined` values, return `undefined`.
+
+```js
+import defined from '@xen-orchestra/defined/index.js'
+
+defined(undefined, 'foo', 42)
+// Returns 'foo'
+
+defined([undefined, null, 10])
+// Returns null
+
+defined([undefined, undefined], [undefined, undefined, 10])
+// Returns [undefined, undefined]
+
+defined(() => 'bar', 42)
+// Returns 'bar'
+
+defined(undefined, undefined)
+// Returns undefined
+```
diff --git a/@xen-orchestra/defined/README.md b/@xen-orchestra/defined/README.md
index 6176dcc500a..942553f41aa 100644
--- a/@xen-orchestra/defined/README.md
+++ b/@xen-orchestra/defined/README.md
@@ -14,6 +14,37 @@ Installation of the [npm package](https://npmjs.org/package/@xen-orchestra/defin
 npm install --save @xen-orchestra/defined
 ```
 
+## Usage
+
+### `defined()`
+
+Returns the first non-`undefined` value from a list of arguments, evaluating functions if needed.
+
+There is two ways to use this function:
+- either with a single array argument: it should return the first non-undefined item
+- or with multiple arguments: it should return the first non-undefined argument
+
+If only `undefined` values, return `undefined`.
+
+```js
+import defined from '@xen-orchestra/defined/index.js'
+
+defined(undefined, 'foo', 42)
+// Returns 'foo'
+
+defined([undefined, null, 10])
+// Returns null
+
+defined([undefined, undefined], [undefined, undefined, 10])
+// Returns [undefined, undefined]
+
+defined(() => 'bar', 42)
+// Returns 'bar'
+
+defined(undefined, undefined)
+// Returns undefined
+```
+
 ## Contributions
 
 Contributions are _very_ welcomed, either on the documentation or on
diff --git a/@xen-orchestra/defined/index.js b/@xen-orchestra/defined/index.js
index 923bb886f02..c95d52c151c 100644
--- a/@xen-orchestra/defined/index.js
+++ b/@xen-orchestra/defined/index.js
@@ -22,7 +22,7 @@ function defined() {
   }
 
   for (let i = 0; i < n; ++i) {
-    let arg = arguments[i]
+    let arg = args[i]
     if (typeof arg === 'function') {
       arg = get(arg)
     }
diff --git a/@xen-orchestra/defined/index.test.mjs b/@xen-orchestra/defined/index.test.mjs
new file mode 100644
index 00000000000..50ed51071bd
--- /dev/null
+++ b/@xen-orchestra/defined/index.test.mjs
@@ -0,0 +1,30 @@
+import { describe, it } from 'node:test'
+import assert from 'node:assert/strict'
+import defined_ from '@xen-orchestra/defined/index.js'
+
+// for each test, use the flat syntax and the array syntax
+for (const [title, defined] of Object.entries({
+  'defined(...values)': defined_,
+  'defined([ ...values ])': (...args) => defined_(args),
+})) {
+  describe(title, () => {
+    it('returns the first non undefined value', () => {
+      assert.deepEqual(defined(undefined, 'foo', 42), 'foo')
+    })
+
+    it('returns undefined if only undefined values', () => {
+      assert.equal(defined(undefined, undefined), undefined)
+    })
+
+    it('resolves functions with `get(fn)`', () => {
+      const o = { foo: undefined, baz: 'baz' }
+      assert.deepEqual(
+        defined(
+          () => o.foo.bar,
+          () => o.baz
+        ),
+        'baz'
+      )
+    })
+  })
+}
diff --git a/@xen-orchestra/defined/package.json b/@xen-orchestra/defined/package.json
index 4f01831508e..b4496d20677 100644
--- a/@xen-orchestra/defined/package.json
+++ b/@xen-orchestra/defined/package.json
@@ -23,6 +23,7 @@
     "node": ">=6"
   },
   "scripts": {
-    "postversion": "npm publish"
+    "postversion": "npm publish",
+    "test": "node --test"
   }
 }
diff --git a/CHANGELOG.unreleased.md b/CHANGELOG.unreleased.md
index b975766a1c9..1f51d541d1d 100644
--- a/CHANGELOG.unreleased.md
+++ b/CHANGELOG.unreleased.md
@@ -41,6 +41,7 @@
 
 <!--packages-start-->
 
+- @xen-orchestra/defined patch
 - @xen-orchestra/lite minor
 - @xen-orchestra/web minor
 - @xen-orchestra/web-core minor