diff --git a/defaultmodules/calendar/calendarutils.js b/defaultmodules/calendar/calendarutils.js
index 751dae2d42..a79e4e9832 100644
--- a/defaultmodules/calendar/calendarutils.js
+++ b/defaultmodules/calendar/calendarutils.js
@@ -109,7 +109,7 @@ const CalendarUtils = {
 					let replacement = transform.replace;
 					if (typeof transform.yearmatchgroup !== "undefined" && transform.yearmatchgroup !== "") {
 						const yearmatch = [...title.matchAll(needle)];
-						if (yearmatch[0].length >= transform.yearmatchgroup + 1 && yearmatch[0][transform.yearmatchgroup] * 1 >= 1900) {
+						if (yearmatch.length > 0 && yearmatch[0].length >= transform.yearmatchgroup + 1 && yearmatch[0][transform.yearmatchgroup] * 1 >= 1900) {
 							const calcage = new Date().getFullYear() - yearmatch[0][transform.yearmatchgroup] * 1;
 							const searchstr = `$${transform.yearmatchgroup}`;
 							replacement = replacement.replace(searchstr, calcage);
diff --git a/tests/unit/modules/default/calendar/calendar_utils_spec.js b/tests/unit/modules/default/calendar/calendar_utils_spec.js
index 77d358ddfa..ef6da28118 100644
--- a/tests/unit/modules/default/calendar/calendar_utils_spec.js
+++ b/tests/unit/modules/default/calendar/calendar_utils_spec.js
@@ -151,5 +151,10 @@ describe("Calendar utils tests", () => {
 			const expectedResult = `Luciella (${new Date().getFullYear() - 2000}.)`;
 			expect(transformedTitle).toBe(expectedResult);
 		});
+
+		it("should not fail when the yearmatchgroup regex does not match", () => {
+			const transformedTitle = CalendarUtils.titleTransform("Test Birthday", [{ search: "^(.+) \\((\\d{4})\\)$", replace: "$1 ($2)", yearmatchgroup: 2 }]);
+			expect(transformedTitle).toBe("Test Birthday");
+		});
 	});
 });