diff --git a/src/TreeNode.js b/src/TreeNode.js
index 6f47f4b..df57fd7 100644
--- a/src/TreeNode.js
+++ b/src/TreeNode.js
@@ -4,6 +4,8 @@ export class TreeNode {
 	constructor(name) {
 		/** @type {string} */
 		this.name = name
+		/** @type {boolean} */
+		this.is_anonymous = false
 		/** @type {Map<string, TreeNode<T>>} */
 		this.children = new Map()
 		/** @type {T[]} */
@@ -11,7 +13,6 @@ export class TreeNode {
 	}
 
 	/**
-	 *
 	 * @param {string[]} path
 	 * @param {string} name
 	 * @param {T} location
@@ -33,6 +34,7 @@ export class TreeNode {
 			// Otherwise, create the item and add the location
 			const new_node = new TreeNode(name)
 			new_node.locations.push(location)
+			new_node.is_anonymous = name.startsWith('__anonymous')
 			current.children.set(name, new_node)
 		}
 	}
@@ -40,6 +42,7 @@ export class TreeNode {
 	/**
 	 * @typedef PlainObject
 	 * @property {string} name
+	 * @property {boolean} is_anonymous
 	 * @property {T[]} locations
 	 * @property {PlainObject[]} children
 	 */
@@ -51,6 +54,7 @@ export class TreeNode {
 	to_plain_object() {
 		return {
 			name: this.name,
+			is_anonymous: this.is_anonymous,
 			locations: this.locations,
 			children: Array
 				.from(this.children.values(), (child) => child.to_plain_object())
diff --git a/test/global.spec.js b/test/global.spec.js
index 668b9d3..4df610a 100644
--- a/test/global.spec.js
+++ b/test/global.spec.js
@@ -25,24 +25,29 @@ test('mixed imports and layers', () => {
 	let expected = [
 		{
 			name: '__anonymous-1__',
+			is_anonymous: true,
 			locations: [{ line: 2, column: 3, start: 3, end: 33 }],
 			children: []
 		},
 		{
 			name: 'test',
+			is_anonymous: false,
 			locations: [{ line: 3, column: 3, start: 36, end: 72 }],
 			children: []
 		},
 		{
 			name: 'anotherTest',
+			is_anonymous: false,
 			locations: [{ line: 4, column: 3, start: 75, end: 148 }],
 			children: [
 				{
 					name: 'moreTest',
+					is_anonymous: false,
 					locations: [{ line: 5, column: 4, start: 99, end: 144 }],
 					children: [
 						{
 							name: 'deepTest',
+							is_anonymous: false,
 							locations: [{ line: 6, column: 5, start: 121, end: 139 }],
 							children: []
 						}
@@ -52,6 +57,7 @@ test('mixed imports and layers', () => {
 		},
 		{
 			name: '__anonymous-2__',
+			is_anonymous: true,
 			locations: [{ line: 10, column: 3, start: 176, end: 185 }],
 			children: []
 		}
diff --git a/test/import.spec.js b/test/import.spec.js
index a5785fd..5e22b83 100644
--- a/test/import.spec.js
+++ b/test/import.spec.js
@@ -6,6 +6,7 @@ test('@import url() layer', () => {
 	let actual = layer_tree('@import url("foo.css") layer;')
 	let expected = [{
 		name: '__anonymous-1__',
+		is_anonymous: true,
 		locations: [{ line: 1, column: 1, start: 0, end: 29 }],
 		children: []
 	}]
@@ -16,6 +17,7 @@ test('@import url() LAYER', () => {
 	let actual = layer_tree('@import url("foo.css") LAYER;')
 	let expected = [{
 		"name": "__anonymous-1__",
+		is_anonymous: true,
 		locations: [{ line: 1, column: 1, start: 0, end: 29 }],
 		"children": []
 	}]
@@ -26,6 +28,7 @@ test('@import url() layer(named)', () => {
 	let actual = layer_tree('@import url("foo.css") layer(named);')
 	let expected = [{
 		name: 'named',
+		is_anonymous: false,
 		locations: [{ line: 1, column: 1, start: 0, end: 36 }],
 		children: []
 	}]
@@ -36,6 +39,7 @@ test('@import url() LAYER(named)', () => {
 	let actual = layer_tree('@import url("foo.css") LAYER(named);')
 	let expected = [{
 		name: 'named',
+		is_anonymous: false,
 		locations: [{ line: 1, column: 1, start: 0, end: 36 }],
 		children: []
 	}]
@@ -46,9 +50,11 @@ test('@import url() layer(named.nested)', () => {
 	let actual = layer_tree('@import url("foo.css") layer(named.nested);')
 	let expected = [{
 		name: 'named',
+		is_anonymous: false,
 		locations: [{ line: 1, column: 1, start: 0, end: 43 }],
 		children: [{
 			name: 'nested',
+			is_anonymous: false,
 			locations: [{ line: 1, column: 1, start: 0, end: 43 }],
 			children: []
 		}]
@@ -60,9 +66,11 @@ test('@import url() layer(named.nested     )', () => {
 	let actual = layer_tree('@import url("foo.css") layer(named.nested     );')
 	let expected = [{
 		name: 'named',
+		is_anonymous: false,
 		locations: [{ line: 1, column: 1, start: 0, end: 48 }],
 		children: [{
 			name: 'nested',
+			is_anonymous: false,
 			locations: [{ line: 1, column: 1, start: 0, end: 48 }],
 			children: []
 		}]
@@ -74,9 +82,11 @@ test('@import url() layer(/* test */named.nested     )', () => {
 	let actual = layer_tree('@import url("foo.css") layer(/* test */named.nested     );')
 	let expected = [{
 		name: 'named',
+		is_anonymous: false,
 		locations: [{ line: 1, column: 1, start: 0, end: 58 }],
 		children: [{
 			name: 'nested',
+			is_anonymous: false,
 			locations: [{ line: 1, column: 1, start: 0, end: 58 }],
 			children: []
 		}]
diff --git a/test/layer.spec.js b/test/layer.spec.js
index 2df12ad..1930bab 100644
--- a/test/layer.spec.js
+++ b/test/layer.spec.js
@@ -7,6 +7,7 @@ test('single anonymous layer without body', () => {
 	let expected = [
 		{
 			name: '__anonymous-1__',
+			is_anonymous: true,
 			children: [],
 			locations: [{ line: 1, column: 1, start: 0, end: 7 }]
 		},
@@ -19,6 +20,7 @@ test('single anonymous layer with body', () => {
 	let expected = [
 		{
 			name: '__anonymous-1__',
+			is_anonymous: true,
 			children: [],
 			locations: [{ line: 1, column: 1, start: 0, end: 9 }]
 		},
@@ -31,6 +33,7 @@ test('single named layer without body', () => {
 	let expected = [
 		{
 			name: 'first',
+			is_anonymous: false,
 			children: [],
 			locations: [{ line: 1, column: 1, start: 0, end: 13 }]
 		},
@@ -43,6 +46,7 @@ test('single named layer with body', () => {
 	let expected = [
 		{
 			name: 'first',
+			is_anonymous: false,
 			children: [],
 			locations: [{ line: 1, column: 1, start: 0, end: 15 }]
 		},
@@ -55,11 +59,13 @@ test('multiple named layers in one line', () => {
 	let expected = [
 		{
 			name: 'first',
+			is_anonymous: false,
 			children: [],
 			locations: [{ line: 1, column: 1, start: 0, end: 21 }]
 		},
 		{
 			name: 'second',
+			is_anonymous: false,
 			children: [],
 			locations: [{ line: 1, column: 1, start: 0, end: 21 }]
 		},
@@ -75,6 +81,7 @@ test('repeated use of the same layer name', () => {
 	let expected = [
 		{
 			name: 'first',
+			is_anonymous: false,
 			children: [],
 			locations: [
 				{ line: 2, column: 3, start: 3, end: 18 },
@@ -98,19 +105,23 @@ test('nested layers', () => {
 	let expected = [
 		{
 			name: 'first',
+			is_anonymous: false,
 			locations: [{ line: 2, column: 3, start: 3, end: 104 }],
 			children: [
 				{
 					name: 'second',
+					is_anonymous: false,
 					locations: [{ line: 3, column: 4, start: 21, end: 100 }],
 					children: [
 						{
 							name: 'third',
+							is_anonymous: false,
 							locations: [{ line: 4, column: 5, start: 41, end: 56 }],
 							children: [],
 						},
 						{
 							name: 'fourth',
+							is_anonymous: false,
 							locations: [{ line: 6, column: 5, start: 79, end: 95 }],
 							children: [],
 						},
@@ -131,10 +142,12 @@ test('nested layers with anonymous layers', () => {
 	let expected = [
 		{
 			name: '__anonymous-1__',
+			is_anonymous: true,
 			locations: [{ line: 2, column: 3, start: 3, end: 28 }],
 			children: [
 				{
 					name: '__anonymous-2__',
+					is_anonymous: true,
 					children: [],
 					locations: [{ line: 3, column: 4, start: 15, end: 24 }],
 				},
@@ -152,11 +165,13 @@ test('consecutive anonymous layers', () => {
 	let expected = [
 		{
 			name: '__anonymous-1__',
+			is_anonymous: true,
 			locations: [{ line: 2, column: 3, start: 3, end: 12 }],
 			children: [],
 		},
 		{
 			name: '__anonymous-2__',
+			is_anonymous: true,
 			locations: [{ line: 3, column: 3, start: 15, end: 24 }],
 			children: [],
 		},
@@ -175,10 +190,12 @@ test('nested layers with anonymous layers and duplicate names', () => {
 	let expected = [
 		{
 			name: '__anonymous-1__',
+			is_anonymous: true,
 			locations: [{ line: 2, column: 3, start: 3, end: 34 }],
 			children: [
 				{
 					name: 'first',
+					is_anonymous: false,
 					children: [],
 					locations: [{ line: 3, column: 4, start: 15, end: 30 }],
 				},
@@ -186,6 +203,7 @@ test('nested layers with anonymous layers and duplicate names', () => {
 		},
 		{
 			name: 'first',
+			is_anonymous: false,
 			locations: [{ line: 6, column: 3, start: 38, end: 53 }],
 			children: [],
 		},