diff --git a/scripts/transform.ts b/scripts/transform.ts
index 02de110..547527a 100644
--- a/scripts/transform.ts
+++ b/scripts/transform.ts
@@ -138,8 +138,8 @@ function addTokenToObject(
 	return obj;
 }
 
-function pxToBaseSize(value: number, decimals = 3) {
-	return (value / BASE_FONT_SIZE).toLocaleString(undefined, {
+export function pxToBaseSize(value: number, decimals = 3) {
+	return (value / BASE_FONT_SIZE).toLocaleString('en', {
 		maximumFractionDigits: decimals,
 	});
 }
diff --git a/tests/transform.spec.ts b/tests/transform.spec.ts
index 5632d1b..1826c59 100644
--- a/tests/transform.spec.ts
+++ b/tests/transform.spec.ts
@@ -1,5 +1,5 @@
 import { expect, test } from 'vitest';
-import { flattenDefaultTokens } from '../scripts/transform';
+import { flattenDefaultTokens, pxToBaseSize } from '../scripts/transform';
 import { TransformedToken } from 'style-dictionary';
 
 const sampleTokens: TransformedToken[] = [
@@ -63,4 +63,6 @@ test('Flatten default tokens', () => {
 			value: 'number',
 		},
 	});
+
+	expect(pxToBaseSize(40)).toEqual('2.857');
 });