diff --git a/packages/utils/src/loader/modern.ts b/packages/utils/src/loader/modern.ts
index cfe9a61..fc5397a 100644
--- a/packages/utils/src/loader/modern.ts
+++ b/packages/utils/src/loader/modern.ts
@@ -22,8 +22,16 @@ export async function searchForIcon(
 		if (iconData) {
 			debug(`${collection}:${id}`);
 			let defaultCustomizations = { ...defaultIconCustomisations };
-			if (typeof customize === 'function')
-				defaultCustomizations = customize(defaultCustomizations);
+			if (typeof customize === 'function') {
+				// Clone icon data to make it mutable
+				iconData = Object.assign({}, iconData);
+				defaultCustomizations =
+					customize(
+						defaultCustomizations,
+						iconData,
+						`${collection}:${id}`
+					) ?? defaultCustomizations;
+			}
 
 			const {
 				attributes: { width, height, ...restAttributes },
diff --git a/packages/utils/src/loader/types.ts b/packages/utils/src/loader/types.ts
index 37e45ec..e58ef91 100644
--- a/packages/utils/src/loader/types.ts
+++ b/packages/utils/src/loader/types.ts
@@ -1,6 +1,6 @@
 import type { Awaitable } from '@antfu/utils';
 import type { FullIconCustomisations } from '../customisations/defaults';
-import type { IconifyJSON } from '@iconify/types';
+import type { IconifyIcon, IconifyJSON } from '@iconify/types';
 
 /**
  * External package name.
@@ -69,11 +69,15 @@ export type IconCustomizations = {
 	 * Change default icon customizations values.
 	 *
 	 * @param defaultCustomizations Default icon's customizations values.
+	 * @param data The icon data. Mutable, you can change the icon data.
+	 * @param name The icon name, can be used to check if icon needs to be customised.
 	 * @return The modified icon's customizations values.
 	 */
 	customize?: (
-		defaultCustomizations: FullIconCustomisations
-	) => FullIconCustomisations;
+		defaultCustomizations: FullIconCustomisations,
+		data: IconifyIcon,
+		name: string
+	) => FullIconCustomisations | undefined;
 	/**
 	 * Custom icon customizer.
 	 */
diff --git a/packages/utils/tests/get-custom-icon-test.ts b/packages/utils/tests/get-custom-icon-test.ts
index 8c51377..fd599d3 100644
--- a/packages/utils/tests/get-custom-icon-test.ts
+++ b/packages/utils/tests/get-custom-icon-test.ts
@@ -143,4 +143,15 @@ describe('Testing getCustomIcon', () => {
 		expect(result && result.indexOf(' width="') === -1).toBeTruthy();
 		expect(result && result.indexOf(' height="') === -1).toBeTruthy();
 	});
+
+	test('CustomIconLoader with non-square icon', async () => {
+		const svg =
+			'<svg viewBox="0 0 90 120"><circle cx="45" cy="60" r="30"/></svg>';
+		const result = await getCustomIcon(() => svg, 'a', 'b', {
+			addXmlNs: true,
+		});
+		expect(result).toEqual(
+			'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 90 120"><circle cx="45" cy="60" r="30"/></svg>'
+		);
+	});
 });
diff --git a/packages/utils/tests/iconify-icon-test.ts b/packages/utils/tests/iconify-icon-test.ts
index 24d300e..286911a 100644
--- a/packages/utils/tests/iconify-icon-test.ts
+++ b/packages/utils/tests/iconify-icon-test.ts
@@ -11,7 +11,7 @@ describe('Testing loadIcon with @iconify-json/flat-color-icons>', () => {
 			addXmlNs: true,
 		});
 		expect(result).toBeTruthy();
-		expect(result && result.indexOf('xmlns:xlink=') === -1).toBeTruthy();
+		expect(result && !result.includes('xmlns:xlink=')).toBeTruthy();
 	});
 
 	test('loadIcon with customize with default style and class', async () => {
@@ -19,7 +19,14 @@ describe('Testing loadIcon with @iconify-json/flat-color-icons>', () => {
 			defaultStyle: 'margin-top: 1rem;',
 			defaultClass: 'clazz',
 			customizations: {
-				customize(props) {
+				customize(props, data, name) {
+					// Check props
+					expect(props.width).toBeNull();
+					expect(data.width).toBe(48);
+					expect(data.height).toBe(48);
+					expect(name).toBe('flat-color-icons:up-right');
+
+					// Change props
 					props.width = '2em';
 					props.height = '2em';
 					return props;
@@ -27,10 +34,10 @@ describe('Testing loadIcon with @iconify-json/flat-color-icons>', () => {
 			},
 		});
 		expect(result).toBeTruthy();
-		expect(result && result.indexOf('margin-top: 1rem;') > -1).toBeTruthy();
-		expect(result && result.indexOf('class="clazz"') > -1).toBeTruthy();
-		expect(result && result.indexOf('width="2em"') > -1).toBeTruthy();
-		expect(result && result.indexOf('height="2em"') > -1).toBeTruthy();
+		expect(result && result.includes('margin-top: 1rem;')).toBeTruthy();
+		expect(result && result.includes('class="clazz"')).toBeTruthy();
+		expect(result && result.includes('width="2em"')).toBeTruthy();
+		expect(result && result.includes('height="2em"')).toBeTruthy();
 	});
 
 	test('loadIcon preserves customizations order', async () => {
@@ -100,7 +107,7 @@ describe('Testing loadIcon with @iconify-json/flat-color-icons>', () => {
 		expect(result && result.includes('height="1em"')).toBeTruthy();
 	});
 
-	test.only('loadIcon with custom width/height', async () => {
+	test('loadIcon with custom width/height', async () => {
 		const result = await loadNodeIcon('flat-color-icons', 'up-right', {
 			customizations: {
 				customize(props) {