diff --git a/components/svelte/tsconfig-base.json b/components/svelte/tsconfig-base.json
index 4a368d1..475695e 100644
--- a/components/svelte/tsconfig-base.json
+++ b/components/svelte/tsconfig-base.json
@@ -7,7 +7,7 @@
 		"declaration": true,
 		"sourceMap": false,
 		"strict": true,
-		"types": ["node", "svelte"],
+		"types": ["svelte"],
 		"moduleResolution": "node",
 		"allowSyntheticDefaultImports": true,
 		"esModuleInterop": true,
diff --git a/packages/core/src/builder/functions.ts b/packages/core/src/builder/functions.ts
index 50621a8..ecb9c68 100644
--- a/packages/core/src/builder/functions.ts
+++ b/packages/core/src/builder/functions.ts
@@ -31,8 +31,6 @@ export function buildIcon(
 ): IconifyIconBuildResult {
 	return iconToSVG(
 		{ ...defaultIconProps, ...icon },
-		customisations
-			? mergeCustomisations(defaultIconCustomisations, customisations)
-			: defaultIconCustomisations
+		mergeCustomisations(defaultIconCustomisations, customisations || {})
 	);
 }
diff --git a/packages/utils/src/customisations/merge.ts b/packages/utils/src/customisations/merge.ts
index 1519ba4..97774a6 100644
--- a/packages/utils/src/customisations/merge.ts
+++ b/packages/utils/src/customisations/merge.ts
@@ -1,4 +1,3 @@
-import { mergeIconTransformations } from '../icon/transformations';
 import {
 	defaultIconSizeCustomisations,
 	FullIconCustomisations,
@@ -7,29 +6,35 @@ import {
 } from './defaults';
 
 /**
- * Convert IconifyIconCustomisations to FullIconCustomisations
+ * Convert IconifyIconCustomisations to FullIconCustomisations, checking value types
  */
 export function mergeCustomisations<T extends FullIconCustomisations>(
 	defaults: T,
-	item: IconifyIconCustomisations,
-	keepOtherProps = true
+	item: IconifyIconCustomisations
 ): T {
-	// Merge transformations
-	const result = mergeIconTransformations(defaults, item, keepOtherProps);
+	// Copy default values
+	const result = {
+		...defaults,
+	};
 
-	// Merge dimensions
-	for (const key in defaultIconSizeCustomisations) {
-		const attr = key as keyof IconifyIconSizeCustomisations;
-
-		const value = item[attr];
+	// Merge all properties
+	for (const key in item) {
+		const value = item[key as keyof IconifyIconCustomisations];
 		const valueType = typeof value;
-		if (
-			value === null ||
-			(value && (valueType === 'string' || valueType === 'number'))
-		) {
-			result[attr] = value;
-		} else {
-			(result as Record<string, unknown>)[attr] = defaults[attr];
+
+		if (key in defaultIconSizeCustomisations) {
+			// Dimension
+			if (
+				value === null ||
+				(value && (valueType === 'string' || valueType === 'number'))
+			) {
+				result[key as keyof IconifyIconSizeCustomisations] =
+					value as string;
+			}
+		} else if (valueType === typeof result[key as keyof T]) {
+			// Normalise rotation, copy everything else as is
+			(result as Record<string, unknown>)[key] =
+				key === 'rotate' ? (value as number) % 4 : value;
 		}
 	}
 
diff --git a/packages/utils/src/icon-set/get-icon.ts b/packages/utils/src/icon-set/get-icon.ts
index 663496a..83ff91d 100644
--- a/packages/utils/src/icon-set/get-icon.ts
+++ b/packages/utils/src/icon-set/get-icon.ts
@@ -1,6 +1,5 @@
-import type { IconifyJSON } from '@iconify/types';
-import { defaultIconProps } from '../icon/defaults';
-import type { IconifyIcon, FullIconifyIcon } from '../icon/defaults';
+import type { ExtendedIconifyIcon, IconifyJSON } from '@iconify/types';
+import { defaultIconProps, FullExtendedIconifyIcon } from '../icon/defaults';
 import { mergeIconData } from '../icon/merge';
 import { getIconsTree } from './tree';
 
@@ -12,30 +11,29 @@ export function internalGetIconData(
 	name: string,
 	tree: string[],
 	full: true
-): FullIconifyIcon;
+): FullExtendedIconifyIcon;
 export function internalGetIconData(
 	data: IconifyJSON,
 	name: string,
 	tree: string[],
 	full: false
-): IconifyIcon;
+): ExtendedIconifyIcon;
 export function internalGetIconData(
 	data: IconifyJSON,
 	name: string,
 	tree: string[],
 	full: boolean
-): FullIconifyIcon | IconifyIcon {
+): FullExtendedIconifyIcon | ExtendedIconifyIcon {
 	const icons = data.icons;
 	const aliases = data.aliases || {};
 
-	let currentProps = {} as IconifyIcon;
+	let currentProps = {} as ExtendedIconifyIcon;
 
 	// Parse parent item
 	function parse(name: string) {
 		currentProps = mergeIconData(
 			icons[name] || aliases[name],
-			currentProps,
-			false
+			currentProps
 		);
 	}
 
@@ -45,9 +43,8 @@ export function internalGetIconData(
 	// Add default values
 	currentProps = mergeIconData(
 		data,
-		currentProps,
-		false
-	) as unknown as IconifyIcon;
+		currentProps
+	) as unknown as ExtendedIconifyIcon;
 
 	// Return icon
 	return full
@@ -62,17 +59,17 @@ export function getIconData(
 	data: IconifyJSON,
 	name: string,
 	full: true
-): FullIconifyIcon | null;
+): FullExtendedIconifyIcon | null;
 export function getIconData(
 	data: IconifyJSON,
 	name: string,
 	full: false
-): IconifyIcon | null;
+): ExtendedIconifyIcon | null;
 export function getIconData(
 	data: IconifyJSON,
 	name: string,
 	full = false
-): FullIconifyIcon | IconifyIcon | null {
+): FullExtendedIconifyIcon | ExtendedIconifyIcon | null {
 	if (data.icons[name]) {
 		// Parse only icon
 		return internalGetIconData(data, name, [], full as true);
diff --git a/packages/utils/src/icon-set/get-icons.ts b/packages/utils/src/icon-set/get-icons.ts
index bed5504..70ae7db 100644
--- a/packages/utils/src/icon-set/get-icons.ts
+++ b/packages/utils/src/icon-set/get-icons.ts
@@ -1,4 +1,4 @@
-import type { IconifyAliases, IconifyJSON } from '@iconify/types';
+import type { IconifyAliases, IconifyIcons, IconifyJSON } from '@iconify/types';
 import { defaultIconDimensions } from '../icon/defaults';
 import { getIconsTree } from './tree';
 
@@ -17,7 +17,7 @@ export function getIcons(
 	names: string[],
 	not_found?: boolean
 ): IconifyJSON | null {
-	const icons = Object.create(null) as IconifyJSON['icons'];
+	const icons = Object.create(null) as IconifyIcons;
 	const aliases = Object.create(null) as IconifyAliases;
 	const result: IconifyJSON = {
 		prefix: data.prefix,
diff --git a/packages/utils/src/icon-set/parse.ts b/packages/utils/src/icon-set/parse.ts
index 93f5981..9ffa954 100644
--- a/packages/utils/src/icon-set/parse.ts
+++ b/packages/utils/src/icon-set/parse.ts
@@ -1,5 +1,5 @@
 import type { IconifyJSON } from '@iconify/types';
-import type { FullIconifyIcon } from '../icon/defaults';
+import type { FullExtendedIconifyIcon } from '../icon/defaults';
 import { internalGetIconData } from './get-icon';
 import { getIconsTree } from './tree';
 
@@ -10,7 +10,7 @@ import { getIconsTree } from './tree';
  */
 export type SplitIconSetCallback = (
 	name: string,
-	data: FullIconifyIcon | null
+	data: FullExtendedIconifyIcon | null
 ) => void;
 
 /**
diff --git a/packages/utils/src/icon-set/tree.ts b/packages/utils/src/icon-set/tree.ts
index c12b98f..6cb3624 100644
--- a/packages/utils/src/icon-set/tree.ts
+++ b/packages/utils/src/icon-set/tree.ts
@@ -43,7 +43,7 @@ export function getIconsTree(
 	}
 
 	// Resolve only required icons
-	(names || Object.keys(aliases).concat(Object.keys(icons))).forEach(resolve);
+	(names || Object.keys(icons).concat(Object.keys(aliases))).forEach(resolve);
 
 	return resolved;
 }
diff --git a/packages/utils/src/icon-set/validate-basic.ts b/packages/utils/src/icon-set/validate-basic.ts
index 7f487bc..4e75d54 100644
--- a/packages/utils/src/icon-set/validate-basic.ts
+++ b/packages/utils/src/icon-set/validate-basic.ts
@@ -1,6 +1,9 @@
 import type { IconifyJSON } from '@iconify/types';
 import { matchIconName } from '../icon/name';
-import { defaultIconDimensions, defaultIconProps } from '../icon/defaults';
+import {
+	defaultIconDimensions,
+	defaultExtendedIconProps,
+} from '../icon/defaults';
 
 type PropsList = Record<string, unknown>;
 
@@ -65,7 +68,10 @@ export function quicklyValidateIconSet(obj: unknown): IconifyJSON | null {
 		if (
 			!name.match(matchIconName) ||
 			typeof icon.body !== 'string' ||
-			!checkOptionalProps(icon as unknown as PropsList, defaultIconProps)
+			!checkOptionalProps(
+				icon as unknown as PropsList,
+				defaultExtendedIconProps
+			)
 		) {
 			return null;
 		}
@@ -80,7 +86,10 @@ export function quicklyValidateIconSet(obj: unknown): IconifyJSON | null {
 			!name.match(matchIconName) ||
 			typeof parent !== 'string' ||
 			(!icons[parent] && !aliases[parent]) ||
-			!checkOptionalProps(icon as unknown as PropsList, defaultIconProps)
+			!checkOptionalProps(
+				icon as unknown as PropsList,
+				defaultExtendedIconProps
+			)
 		) {
 			return null;
 		}
diff --git a/packages/utils/src/icon-set/validate.ts b/packages/utils/src/icon-set/validate.ts
index 11c3f7b..ae1040d 100644
--- a/packages/utils/src/icon-set/validate.ts
+++ b/packages/utils/src/icon-set/validate.ts
@@ -4,7 +4,7 @@ import type {
 	IconifyOptional,
 } from '@iconify/types';
 import { matchIconName } from '../icon/name';
-import { defaultIconProps } from '../icon/defaults';
+import { defaultExtendedIconProps } from '../icon/defaults';
 import { getIconsTree } from './tree';
 
 /**
@@ -34,10 +34,9 @@ function validateIconProps(
 			continue;
 		}
 
-		const expectedType =
-			key === 'hidden'
-				? 'boolean'
-				: typeof (defaultIconProps as Record<string, unknown>)[attr];
+		const expectedType = typeof (
+			defaultExtendedIconProps as Record<string, unknown>
+		)[attr];
 
 		if (expectedType !== 'undefined') {
 			if (type !== expectedType) {
diff --git a/packages/utils/src/icon/defaults.ts b/packages/utils/src/icon/defaults.ts
index 6ad034d..9067630 100644
--- a/packages/utils/src/icon/defaults.ts
+++ b/packages/utils/src/icon/defaults.ts
@@ -3,12 +3,20 @@ import type {
 	IconifyTransformations,
 	IconifyOptional,
 	IconifyIcon,
+	ExtendedIconifyIcon,
 } from '@iconify/types';
 
 // Export icon and full icon types
 export { IconifyIcon };
+
 export type FullIconifyIcon = Required<IconifyIcon>;
 
+// Partial and full extended icon
+export type PartialExtendedIconifyIcon = Partial<ExtendedIconifyIcon>;
+
+type IconifyIconExtraProps = Omit<ExtendedIconifyIcon, keyof IconifyIcon>;
+export type FullExtendedIconifyIcon = FullIconifyIcon & IconifyIconExtraProps;
+
 /**
  * Default values for dimensions
  */
@@ -38,3 +46,13 @@ export const defaultIconProps: Required<IconifyOptional> = Object.freeze({
 	...defaultIconDimensions,
 	...defaultIconTransformations,
 });
+
+/**
+ * Default values for all properties used in ExtendedIconifyIcon
+ */
+export const defaultExtendedIconProps: Required<FullExtendedIconifyIcon> =
+	Object.freeze({
+		...defaultIconProps,
+		body: '',
+		hidden: false,
+	});
diff --git a/packages/utils/src/icon/merge.ts b/packages/utils/src/icon/merge.ts
index d541545..816072c 100644
--- a/packages/utils/src/icon/merge.ts
+++ b/packages/utils/src/icon/merge.ts
@@ -1,43 +1,42 @@
-import type {
-	IconifyDimenisons,
-	IconifyIcon,
-	IconifyOptional,
-	IconifyTransformations,
-} from '@iconify/types';
-import { defaultIconDimensions } from './defaults';
+import type { IconifyTransformations } from '@iconify/types';
+import {
+	defaultExtendedIconProps,
+	defaultIconTransformations,
+	PartialExtendedIconifyIcon,
+} from './defaults';
 import { mergeIconTransformations } from './transformations';
 
-// Props to copy: all icon properties, except transformations
-type PropsToCopy = Omit<IconifyIcon, keyof IconifyTransformations>;
-const propsToMerge: Required<PropsToCopy> = {
-	...defaultIconDimensions,
-	body: '',
-};
-
 /**
  * Merge icon and alias
  *
  * Can also be used to merge default values and icon
  */
-export function mergeIconData<T extends IconifyOptional>(
+export function mergeIconData<T extends PartialExtendedIconifyIcon>(
 	parent: T,
-	child: IconifyOptional | IconifyIcon,
-	keepOtherParentProps = true
+	child: PartialExtendedIconifyIcon
 ): T {
-	// Merge transformations
-	const result = mergeIconTransformations(
-		parent,
-		child,
-		keepOtherParentProps
-	);
+	// Merge transformations and add defaults
+	const result = mergeIconTransformations(parent, child);
 
 	// Merge icon properties that aren't transformations
-	for (const key in propsToMerge) {
-		const prop = key as keyof IconifyDimenisons;
-		if (child[prop] !== void 0) {
-			result[prop] = child[prop];
-		} else if (parent[prop] !== void 0) {
-			result[prop] = parent[prop];
+	for (const key in defaultExtendedIconProps) {
+		// Add default transformations if needed
+		if (
+			defaultIconTransformations[key as keyof IconifyTransformations] !==
+			void 0
+		) {
+			if (
+				result[key as 'rotate'] === void 0 &&
+				parent[key as keyof T] !== void 0
+			) {
+				result[key as 'rotate'] =
+					defaultIconTransformations[key as 'rotate'];
+			}
+			// Not transformation
+		} else if (child[key as 'width'] !== void 0) {
+			result[key as 'width'] = child[key as 'width'];
+		} else if (parent[key as 'width'] !== void 0) {
+			result[key as 'width'] = parent[key as 'width'];
 		}
 	}
 
diff --git a/packages/utils/src/icon/transformations.ts b/packages/utils/src/icon/transformations.ts
index 047cfe6..9efcbdf 100644
--- a/packages/utils/src/icon/transformations.ts
+++ b/packages/utils/src/icon/transformations.ts
@@ -5,18 +5,18 @@ import type { IconifyTransformations } from '@iconify/types';
  */
 export function mergeIconTransformations<T extends IconifyTransformations>(
 	obj1: T,
-	obj2: IconifyTransformations,
-	keepOtherProps = true
+	obj2: IconifyTransformations
 ): T {
-	const result = keepOtherProps ? { ...obj1 } : ({} as T);
-	if (obj1.hFlip || obj2.hFlip) {
-		result.hFlip = obj1.hFlip !== obj2.hFlip;
+	const result = {} as T;
+	if (!obj1.hFlip !== !obj2.hFlip) {
+		result.hFlip = true;
 	}
-	if (obj1.vFlip || obj2.vFlip) {
-		result.vFlip = obj1.vFlip !== obj2.vFlip;
+	if (!obj1.vFlip !== !obj2.vFlip) {
+		result.vFlip = true;
 	}
-	if (obj1.rotate || obj2.rotate) {
-		result.rotate = ((obj1.rotate || 0) + (obj2.rotate || 0)) % 4;
+	const rotate = ((obj1.rotate || 0) + (obj2.rotate || 0)) % 4;
+	if (rotate) {
+		result.rotate = rotate;
 	}
 	return result;
 }
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index d4fdcdf..f85ea97 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -19,6 +19,7 @@ export {
 
 // Icon data
 export { mergeIconData } from './icon/merge';
+export { mergeIconTransformations } from './icon/transformations';
 export {
 	defaultIconProps,
 	defaultIconDimensions,
diff --git a/packages/utils/src/svg/build.ts b/packages/utils/src/svg/build.ts
index 752bc55..ccd0df4 100644
--- a/packages/utils/src/svg/build.ts
+++ b/packages/utils/src/svg/build.ts
@@ -160,7 +160,8 @@ export function iconToSVG(
 	const boxWidth = box.width;
 	const boxHeight = box.height;
 
-	let width, height;
+	let width: string | number;
+	let height: string | number;
 	if (customisationsWidth === null) {
 		// Width is not set: calculate width from height, default to '1em'
 		height =
@@ -181,15 +182,11 @@ export function iconToSVG(
 				: customisationsHeight;
 	}
 
-	// Convert to string
-	width = typeof width === 'string' ? width : width.toString();
-	height = typeof height === 'string' ? height : height.toString();
-
 	// Result
 	const result: IconifyIconBuildResult = {
 		attributes: {
-			width,
-			height,
+			width: width.toString(),
+			height: height.toString(),
 			viewBox:
 				box.left.toString() +
 				' ' +
diff --git a/packages/utils/tests/merge-icon-data-test.ts b/packages/utils/tests/merge-icon-data-test.ts
index 432e68a..ff79f39 100644
--- a/packages/utils/tests/merge-icon-data-test.ts
+++ b/packages/utils/tests/merge-icon-data-test.ts
@@ -2,8 +2,7 @@ import type { IconifyIcon } from '@iconify/types';
 import { mergeIconData } from '../lib/icon/merge';
 
 describe('Testing merging icon data', () => {
-	test('Test', () => {
-		// Nothing to merge
+	test('Nothing to merge', () => {
 		const icon: IconifyIcon = {
 			body: '<g />',
 		};
@@ -13,9 +12,10 @@ describe('Testing merging icon data', () => {
 		// Check hint manually: supposed to be IconifyIcon
 		const result = mergeIconData(icon, {});
 		expect(result).toEqual(expected);
+	});
 
-		// TypeScript full icon test
-		const icon2: Required<IconifyIcon> = {
+	test('Full icons', () => {
+		const icon: Required<IconifyIcon> = {
 			body: '<g />',
 			width: 24,
 			height: 24,
@@ -25,7 +25,7 @@ describe('Testing merging icon data', () => {
 			hFlip: false,
 			vFlip: false,
 		};
-		const expected2: Required<IconifyIcon> = {
+		const expected: Required<IconifyIcon> = {
 			body: '<g />',
 			width: 24,
 			height: 24,
@@ -36,9 +36,11 @@ describe('Testing merging icon data', () => {
 			vFlip: false,
 		};
 		// Check hint manually: supposed to be Required<IconifyIcon>
-		const result2 = mergeIconData(icon2, {});
-		expect(result2).toEqual(expected2);
+		const result = mergeIconData(icon, {});
+		expect(result).toEqual(expected);
+	});
 
+	test('Copy values', () => {
 		// Copy values
 		expect(
 			mergeIconData(
@@ -55,8 +57,9 @@ describe('Testing merging icon data', () => {
 			width: 24,
 			height: 32,
 		});
+	});
 
-		// Override values
+	test('Override values', () => {
 		expect(
 			mergeIconData(
 				{
@@ -74,4 +77,30 @@ describe('Testing merging icon data', () => {
 			height: 32,
 		});
 	});
+
+	test('Override transformations', () => {
+		expect(
+			mergeIconData(
+				{
+					body: '<g />',
+					width: 24,
+					height: 24,
+					hFlip: true,
+					rotate: 3,
+				},
+				{
+					height: 32,
+					vFlip: true,
+					rotate: 2,
+				}
+			)
+		).toEqual({
+			body: '<g />',
+			width: 24,
+			height: 32,
+			hFlip: true,
+			vFlip: true,
+			rotate: 1,
+		});
+	});
 });
diff --git a/packages/utils/tests/svg-build-test.ts b/packages/utils/tests/svg-build-test.ts
index 06a0342..027843b 100644
--- a/packages/utils/tests/svg-build-test.ts
+++ b/packages/utils/tests/svg-build-test.ts
@@ -4,7 +4,6 @@ import type { FullIconifyIcon } from '../lib/icon/defaults';
 import { defaultIconProps } from '../lib/icon/defaults';
 import type { FullIconCustomisations } from '../lib/customisations/defaults';
 import { defaultIconCustomisations } from '../lib/customisations/defaults';
-import { mergeCustomisations } from '../lib/customisations/merge';
 import { iconToHTML } from '../lib/svg/html';
 
 describe('Testing iconToSVG', () => {
@@ -31,12 +30,10 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Auto size, body', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				height: 'auto',
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			height: 'auto',
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			body: '<path d="" />',
@@ -66,12 +63,10 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Auto size, body', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				height: 'auto',
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			height: 'auto',
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			body: '<path d="" />',
@@ -90,12 +85,10 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Custom size', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				height: 'auto',
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			height: 'auto',
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			width: 20,
@@ -116,13 +109,11 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Rotation', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				height: '40px',
-				rotate: 1,
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			height: '40px',
+			rotate: 1,
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			width: 20,
@@ -143,13 +134,11 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Negative rotation', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				height: '40px',
-				rotate: -1,
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			height: '40px',
+			rotate: -1,
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			width: 20,
@@ -170,13 +159,11 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Flip', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				height: '32',
-				hFlip: true,
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			height: '32',
+			hFlip: true,
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			width: 20,
@@ -197,13 +184,11 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Flip, rotation', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				hFlip: true,
-				rotate: 1,
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			hFlip: true,
+			rotate: 1,
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			width: 20,
@@ -224,12 +209,10 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Flip icon that is rotated by default', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				hFlip: true,
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			hFlip: true,
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			width: 20,
@@ -254,16 +237,14 @@ describe('Testing iconToSVG', () => {
 	});
 
 	test('Flip and rotation canceling eachother', () => {
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{
-				width: '1em',
-				height: 'auto',
-				hFlip: true,
-				vFlip: true,
-				rotate: 2,
-			}
-		);
+		const custom: FullIconCustomisations = {
+			...defaultIconCustomisations,
+			width: '1em',
+			height: 'auto',
+			hFlip: true,
+			vFlip: true,
+			rotate: 2,
+		};
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			width: 20,
@@ -287,10 +268,7 @@ describe('Testing iconToSVG', () => {
 		const iconBody =
 			'<g stroke="currentColor" stroke-width="16" stroke-linecap="round" stroke-linejoin="round" fill="none" fill-rule="evenodd"><path d="M40 64l48-48" class="animation-delay-0 animation-duration-10 animate-stroke stroke-length-102"/><path d="M40 64l48 48" class="animation-delay-0 animation-duration-10 animate-stroke stroke-length-102"/></g>';
 
-		const custom: FullIconCustomisations = mergeCustomisations(
-			defaultIconCustomisations,
-			{}
-		);
+		const custom: FullIconCustomisations = defaultIconCustomisations;
 		const icon: FullIconifyIcon = {
 			...defaultIconProps,
 			body: iconBody,