diff --git a/test/built-ins/Temporal/PlainDate/from/monthcode-invalid.js b/test/built-ins/Temporal/PlainDate/from/monthcode-invalid.js
new file mode 100644
index 0000000000..c42c69018d
--- /dev/null
+++ b/test/built-ins/Temporal/PlainDate/from/monthcode-invalid.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.from
+description: Validation of monthCode
+features: [Temporal]
+---*/
+
+["m1", "M1", "m01"].forEach((monthCode) => {
+  assert.throws(RangeError, () => Temporal.PlainDate.from({ year: 2021, monthCode, day: 17 }),
+    `monthCode '${monthCode}' is not well-formed`);
+});
+
+assert.throws(RangeError, () => Temporal.PlainDate.from({ year: 2021, month: 12, monthCode: "M11", day: 17 }),
+  "monthCode and month conflict");
+
+["M00", "M19", "M99", "M13", "M00L", "M05L", "M13L"].forEach((monthCode) => {
+  assert.throws(RangeError, () => Temporal.PlainDate.from({ year: 2021, monthCode, day: 17 }),
+    `monthCode '${monthCode}' is not valid for ISO 8601 calendar`);
+});
+
+assert.throws(
+  RangeError,
+  () => Temporal.PlainDate.from({ day: 1, monthCode: "L99M", year: Symbol() }),
+  "Month code syntax is validated before year type is validated"
+);
+
+assert.throws(
+  TypeError,
+  () => Temporal.PlainDate.from({ day: 1, monthCode: "M99L", year: Symbol() }),
+  "Month code suitability is validated after year type is validated"
+);
diff --git a/test/built-ins/Temporal/PlainDateTime/from/monthcode-invalid.js b/test/built-ins/Temporal/PlainDateTime/from/monthcode-invalid.js
new file mode 100644
index 0000000000..2cc9a67cef
--- /dev/null
+++ b/test/built-ins/Temporal/PlainDateTime/from/monthcode-invalid.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindatetime.from
+description: Validation of monthCode
+features: [Temporal]
+---*/
+
+["m1", "M1", "m01"].forEach((monthCode) => {
+  assert.throws(RangeError, () => Temporal.PlainDateTime.from({ year: 2021, monthCode, day: 17 }),
+    `monthCode '${monthCode}' is not well-formed`);
+});
+
+assert.throws(RangeError, () => Temporal.PlainDateTime.from({ year: 2021, month: 12, monthCode: "M11", day: 17 }),
+  "monthCode and month conflict");
+
+["M00", "M19", "M99", "M13", "M00L", "M05L", "M13L"].forEach((monthCode) => {
+  assert.throws(RangeError, () => Temporal.PlainDateTime.from({ year: 2021, monthCode, day: 17 }),
+    `monthCode '${monthCode}' is not valid for ISO 8601 calendar`);
+});
+
+assert.throws(
+  RangeError,
+  () => Temporal.PlainDateTime.from({ day: 1, monthCode: "L99M", year: Symbol() }),
+  "Month code syntax is validated before year type is validated"
+);
+
+assert.throws(
+  TypeError,
+  () => Temporal.PlainDateTime.from({ day: 1, monthCode: "M99L", year: Symbol() }),
+  "Month code suitability is validated after year type is validated"
+);
diff --git a/test/built-ins/Temporal/PlainMonthDay/from/monthcode-invalid.js b/test/built-ins/Temporal/PlainMonthDay/from/monthcode-invalid.js
index 4957e52178..8685df78a2 100644
--- a/test/built-ins/Temporal/PlainMonthDay/from/monthcode-invalid.js
+++ b/test/built-ins/Temporal/PlainMonthDay/from/monthcode-invalid.js
@@ -15,7 +15,19 @@ features: [Temporal]
 assert.throws(RangeError, () => Temporal.PlainMonthDay.from({ year: 2021, month: 12, monthCode: "M11", day: 17 }),
   "monthCode and month conflict");
 
-["M00", "M19", "M99", "M13"].forEach((monthCode) => {
+["M00", "M19", "M99", "M13", "M00L", "M05L", "M13L"].forEach((monthCode) => {
   assert.throws(RangeError, () => Temporal.PlainMonthDay.from({ monthCode, day: 17 }),
     `monthCode '${monthCode}' is not valid for ISO 8601 calendar`);
 });
+
+assert.throws(
+  RangeError,
+  () => Temporal.PlainMonthDay.from({ day: 1, monthCode: "L99M", year: Symbol() }),
+  "Month code syntax is validated before year type is validated"
+);
+
+assert.throws(
+  TypeError,
+  () => Temporal.PlainMonthDay.from({ day: 1, monthCode: "M99L", year: Symbol() }),
+  "Month code suitability is validated after year type is validated"
+);
diff --git a/test/built-ins/Temporal/PlainYearMonth/from/monthcode-invalid.js b/test/built-ins/Temporal/PlainYearMonth/from/monthcode-invalid.js
index 84357f8890..b52a7f3d29 100644
--- a/test/built-ins/Temporal/PlainYearMonth/from/monthcode-invalid.js
+++ b/test/built-ins/Temporal/PlainYearMonth/from/monthcode-invalid.js
@@ -15,7 +15,19 @@ features: [Temporal]
 assert.throws(RangeError, () => Temporal.PlainYearMonth.from({ year: 2021, month: 12, monthCode: "M11" }),
      "monthCode and month conflict");
 
-["M00", "M19", "M99", "M13"].forEach((monthCode) => {
+["M00", "M19", "M99", "M13", "M00L", "M05L", "M13L"].forEach((monthCode) => {
   assert.throws(RangeError, () => Temporal.PlainYearMonth.from({ year: 2021, monthCode }),
-    `monthCode '${monthCode}' is not valid for year 2021`);
+    `monthCode '${monthCode}' is not valid for year 2021 in ISO 8601 calendar`);
 });
+
+assert.throws(
+  RangeError,
+  () => Temporal.PlainYearMonth.from({ monthCode: "L99M", year: Symbol() }),
+  "Month code syntax is validated before year type is validated"
+);
+
+assert.throws(
+  TypeError,
+  () => Temporal.PlainYearMonth.from({ monthCode: "M99L", year: Symbol() }),
+  "Month code suitability is validated after year type is validated"
+);
diff --git a/test/built-ins/Temporal/ZonedDateTime/from/monthcode-invalid.js b/test/built-ins/Temporal/ZonedDateTime/from/monthcode-invalid.js
new file mode 100644
index 0000000000..92e30d43ad
--- /dev/null
+++ b/test/built-ins/Temporal/ZonedDateTime/from/monthcode-invalid.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2024 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.zoneddatetime.from
+description: Validation of monthCode
+features: [Temporal]
+---*/
+
+["m1", "M1", "m01"].forEach((monthCode) => {
+  assert.throws(RangeError, () => Temporal.ZonedDateTime.from({ year: 2021, monthCode, day: 17, timeZone: "UTC" }),
+    `monthCode '${monthCode}' is not well-formed`);
+});
+
+assert.throws(RangeError, () => Temporal.ZonedDateTime.from({ year: 2021, month: 12, monthCode: "M11", day: 17, timeZone: "UTC" }),
+  "monthCode and month conflict");
+
+["M00", "M19", "M99", "M13", "M00L", "M05L", "M13L"].forEach((monthCode) => {
+  assert.throws(RangeError, () => Temporal.ZonedDateTime.from({ year: 2021, monthCode, day: 17, timeZone: "UTC" }),
+    `monthCode '${monthCode}' is not valid for ISO 8601 calendar`);
+});
+
+assert.throws(
+  RangeError,
+  () => Temporal.ZonedDateTime.from({ day: 1, monthCode: "L99M", year: Symbol(), timeZone: "UTC" }),
+  "Month code syntax is validated before year type is validated"
+);
+
+assert.throws(
+  TypeError,
+  () => Temporal.ZonedDateTime.from({ day: 1, monthCode: "M99L", year: Symbol(), timeZone: "UTC" }),
+  "Month code suitability is validated after year type is validated"
+);