diff --git a/tests/utils.test.js b/tests/utils.test.js
index 7c38c7f..f2a9717 100644
--- a/tests/utils.test.js
+++ b/tests/utils.test.js
@@ -89,3 +89,10 @@ suite('Bilirubin display', () => {
 		assert.equal(prettyPrintBilirubin(90.99), '91');
 	});
 });
+
+suite('Date to ISO string', () => {
+	test('Date to ISO string', () => {
+		let date = new Date(2024, 11, 25, 4, 20, 31, 415);  // Wed Dec 25 2024 04:20:31 GMT+1100 (Australian Eastern Daylight Time)
+		assert.equal(dateToISOStringLocal(date), '2024-12-25T04:20');
+	});
+});