diff --git a/test/intl402/DateTimeFormat/canonicalize-calendar.js b/test/intl402/DateTimeFormat/canonicalize-calendar.js
new file mode 100644
index 0000000000..ab38e64240
--- /dev/null
+++ b/test/intl402/DateTimeFormat/canonicalize-calendar.js
@@ -0,0 +1,23 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-intl.datetimeformat
+description: Calendar IDs are canonicalized
+locale: [en, en-u-ca-islamic-civil]
+---*/
+
+const fmt1 = new Intl.DateTimeFormat("en", { calendar: "islamicc" });
+assert.sameValue(fmt1.resolvedOptions().calendar, "islamic-civil", "calendar ID is canonicalized (option)");
+
+const fmt2 = new Intl.DateTimeFormat("en-u-ca-islamicc");
+assert.sameValue(fmt1.resolvedOptions().calendar, "islamic-civil", "calendar ID is canonicalized (locale key)");
+
+const fmt3 = new Intl.DateTimeFormat("en", { calendar: "ISO8601" });
+assert.sameValue(fmt3.resolvedOptions().calendar, "iso8601", "calendar ID is lowercased");
+
+assert.throws(
+  RangeError,
+  () => new Intl.DateTimeFormat("en", { calendar: "\u0130SO8601" }),
+  "calendar ID is capital dotted I is not lowercased (first argument)"
+);