diff --git a/test/built-ins/Temporal/Instant/from/argument-string.js b/test/built-ins/Temporal/Instant/from/argument-string.js
index 3b75ad65a4..be1af8ee42 100644
--- a/test/built-ins/Temporal/Instant/from/argument-string.js
+++ b/test/built-ins/Temporal/Instant/from/argument-string.js
@@ -37,6 +37,14 @@ const tests = [
   ['1976-11-18T15:23:30+00', 217178610000000000n],
   ['1976-11-18T15Z', 217177200000000000n],
   ['1976-11-18T15:23:30.123456789Z[u-ca=discord]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[+00]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[+00:00]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[-00]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[-00:00]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[+12]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[UTC]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[Europe/Paris]', 217178610123456789n],
+  ['1976-11-18T15:23:30.123456789Z[NotATimeZone]', 217178610123456789n],
 ];
 
 for (const [arg, expected] of tests) {