diff --git a/harness/temporalHelpers.js b/harness/temporalHelpers.js
index 6f76d4d8e5..3a2ed5e4d4 100644
--- a/harness/temporalHelpers.js
+++ b/harness/temporalHelpers.js
@@ -1191,13 +1191,23 @@ var TemporalHelpers = {
    * will log any calls to its accessors to the array @calls.
    */
   observeProperty(calls, object, propertyName, value) {
+    let displayName = propertyName;
+    if (typeof propertyName === 'symbol') {
+      if (Symbol.keyFor(propertyName) !== undefined) {
+        displayName = `[Symbol.for('${Symbol.keyFor(propertyName)}')]`;
+      } else if (propertyName.description.startsWith('Symbol.')) {
+        displayName = `[${propertyName.description}]`;
+      } else {
+        displayName = `[Symbol('${propertyName.description}')]`
+      }
+    }
     Object.defineProperty(object, propertyName, {
       get() {
-        calls.push(`get ${propertyName}`);
+        calls.push(`get ${displayName}`);
         return value;
       },
       set(v) {
-        calls.push(`set ${propertyName}`);
+        calls.push(`set ${displayName}`);
       }
     });
   },
diff --git a/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/custom-timezone.js b/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/custom-timezone.js
index 7b831f0f11..906d3dfef8 100644
--- a/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/custom-timezone.js
+++ b/test/built-ins/Temporal/TimeZone/prototype/getPlainDateTimeFor/custom-timezone.js
@@ -10,28 +10,18 @@ features: [Temporal]
 
 const actual = [];
 const expected = [
-  "get timeZone.getOffsetNanosecondsFor",
+  "get getOffsetNanosecondsFor",
   "call timeZone.getOffsetNanosecondsFor",
 ];
 
 const instant = Temporal.Instant.from("1975-02-02T14:25:36.123456789Z");
-const timeZone = new Proxy({
-  getOffsetNanosecondsFor(instantArg) {
-    actual.push("call timeZone.getOffsetNanosecondsFor");
-    assert.sameValue(instantArg, instant);
-    return 9876543210123;
-  },
-}, {
-  has(target, property) {
-    actual.push(`has timeZone.${property}`);
-    return property in target;
-  },
-  get(target, property) {
-    actual.push(`get timeZone.${property}`);
-    return target[property];
-  },
+const timeZone = new Temporal.TimeZone("UTC");
+TemporalHelpers.observeProperty(actual, timeZone, "getOffsetNanosecondsFor", function (instantArg) {
+  actual.push("call timeZone.getOffsetNanosecondsFor");
+  assert.sameValue(instantArg, instant);
+  return 9876543210123;
 });
 
-const result = Temporal.TimeZone.prototype.getPlainDateTimeFor.call(timeZone, instant);
+const result = timeZone.getPlainDateTimeFor(instant);
 TemporalHelpers.assertPlainDateTime(result, 1975, 2, "M02", 2, 17, 10, 12, 666, 666, 912);
 assert.compareArray(actual, expected);
diff --git a/test/built-ins/Temporal/TimeZone/prototype/id/custom-timezone.js b/test/built-ins/Temporal/TimeZone/prototype/id/custom-timezone.js
new file mode 100644
index 0000000000..1ea8713ab2
--- /dev/null
+++ b/test/built-ins/Temporal/TimeZone/prototype/id/custom-timezone.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2020 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-get-temporal.timezone.prototype.id
+description: Getter calls toString() and returns its value
+includes: [compareArray.js, temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const actual = [];
+const expected = [
+  "get [Symbol.toPrimitive]",
+  "get toString",
+  "call timeZone.toString",
+];
+
+const timeZone = new Temporal.TimeZone("UTC");
+TemporalHelpers.observeProperty(actual, timeZone, Symbol.toPrimitive, undefined);
+TemporalHelpers.observeProperty(actual, timeZone, "toString", function () {
+  actual.push("call timeZone.toString");
+  return "time zone";
+});
+
+const result = timeZone.id;
+assert.compareArray(actual, expected);
+assert.sameValue(result, "time zone");
diff --git a/test/built-ins/Temporal/TimeZone/prototype/id/no-toString.js b/test/built-ins/Temporal/TimeZone/prototype/id/no-toString.js
index d9d457a1c4..ae849b0f83 100644
--- a/test/built-ins/Temporal/TimeZone/prototype/id/no-toString.js
+++ b/test/built-ins/Temporal/TimeZone/prototype/id/no-toString.js
@@ -21,6 +21,5 @@ Object.defineProperty(timeZone, "toString", {
   },
 });
 
-const descriptor = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "id");
-assert.throws(TypeError, () => descriptor.get.call(timeZone));
+assert.throws(TypeError, () => timeZone.id);
 assert.compareArray(actual, expected);
diff --git a/test/built-ins/Temporal/TimeZone/prototype/id/plain-custom-timezone.js b/test/built-ins/Temporal/TimeZone/prototype/id/plain-custom-timezone.js
deleted file mode 100644
index d5cf02a59b..0000000000
--- a/test/built-ins/Temporal/TimeZone/prototype/id/plain-custom-timezone.js
+++ /dev/null
@@ -1,45 +0,0 @@
-// Copyright (C) 2020 Igalia, S.L. All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-esid: sec-get-temporal.timezone.prototype.id
-description: Getter calls toString() and returns its value
-includes: [compareArray.js]
-features: [Temporal]
----*/
-
-const actual = [];
-const expected = [
-  "get timeZone[@@toPrimitive]",
-  "get timeZone.toString",
-  "call timeZone.toString",
-];
-
-const timeZone = new Proxy({
-  toString() {
-    actual.push("call timeZone.toString");
-    return "time zone";
-  },
-}, {
-  has(target, property) {
-    if (property === Symbol.toPrimitive) {
-      actual.push('has timeZone[@@toPrimitive]');
-    } else {
-      actual.push(`has timeZone.${property}`);
-    }
-    return property in target;
-  },
-  get(target, property) {
-    if (property === Symbol.toPrimitive) {
-      actual.push('get timeZone[@@toPrimitive]');
-    } else {
-      actual.push(`get timeZone.${property}`);
-    }
-    return target[property];
-  },
-});
-
-const descriptor = Object.getOwnPropertyDescriptor(Temporal.TimeZone.prototype, "id");
-const result = descriptor.get.call(timeZone);
-assert.compareArray(actual, expected);
-assert.sameValue(result, "time zone");
diff --git a/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-call.js b/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-call.js
index 537a7c3e15..2d59752680 100644
--- a/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-call.js
+++ b/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-call.js
@@ -4,44 +4,24 @@
 /*---
 esid: sec-temporal.timezone.prototype.tojson
 description: toJSON() calls toString() and returns its value
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
 const actual = [];
 const expected = [
-  'get timeZone[@@toPrimitive]',
-  'get timeZone.toString',
+  'get [Symbol.toPrimitive]',
+  'get toString',
   'call timeZone.toString',
 ];
 
-const timeZone = new Proxy(
-  {
-    toString() {
-      actual.push(`call timeZone.toString`);
-      return 'Etc/TAI';
-    }
-  },
-  {
-    has(target, property) {
-      if (property === Symbol.toPrimitive) {
-        actual.push('has timeZone[@@toPrimitive]');
-      } else {
-        actual.push(`has timeZone.${property}`);
-      }
-      return property in target;
-    },
-    get(target, property) {
-      if (property === Symbol.toPrimitive) {
-        actual.push('get timeZone[@@toPrimitive]');
-      } else {
-        actual.push(`get timeZone.${property}`);
-      }
-      return target[property];
-    }
-  }
-);
+const timeZone = new Temporal.TimeZone("UTC");
+TemporalHelpers.observeProperty(actual, timeZone, Symbol.toPrimitive, undefined);
+TemporalHelpers.observeProperty(actual, timeZone, "toString", function () {
+  actual.push("call timeZone.toString");
+  return "Etc/TAI";
+});
 
-const result = Temporal.TimeZone.prototype.toJSON.call(timeZone);
+const result = timeZone.toJSON();
 assert.sameValue(result, 'Etc/TAI', 'toString');
 assert.compareArray(actual, expected);
diff --git a/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-undefined-custom.js b/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-undefined-custom.js
index d3411cbd6e..bf9b82e08e 100644
--- a/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-undefined-custom.js
+++ b/test/built-ins/Temporal/TimeZone/prototype/toJSON/tostring-undefined-custom.js
@@ -4,40 +4,21 @@
 /*---
 esid: sec-temporal.timezone.prototype.tojson
 description: TypeError thrown when toString property not present
-includes: [compareArray.js]
+includes: [compareArray.js, temporalHelpers.js]
 features: [Temporal]
 ---*/
 
 const actual = [];
 const expected = [
-  'get timeZone[@@toPrimitive]',
-  'get timeZone.toString',
-  'get timeZone.valueOf',
+  'get [Symbol.toPrimitive]',
+  'get toString',
+  'get valueOf',
 ];
 
-const timeZone = new Proxy(
-  {
-    toString: undefined
-  },
-  {
-    has(target, property) {
-      if (property === Symbol.toPrimitive) {
-        actual.push('has timeZone[@@toPrimitive]');
-      } else {
-        actual.push(`has timeZone.${property}`);
-      }
-      return property in target;
-    },
-    get(target, property) {
-      if (property === Symbol.toPrimitive) {
-        actual.push('get timeZone[@@toPrimitive]');
-      } else {
-        actual.push(`get timeZone.${property}`);
-      }
-      return target[property];
-    }
-  }
-);
+const timeZone = new Temporal.TimeZone("UTC");
+TemporalHelpers.observeProperty(actual, timeZone, Symbol.toPrimitive, undefined);
+TemporalHelpers.observeProperty(actual, timeZone, "toString", undefined);
+TemporalHelpers.observeProperty(actual, timeZone, "valueOf", Object.prototype.valueOf);
 
-assert.throws(TypeError, () => Temporal.TimeZone.prototype.toJSON.call(timeZone));
+assert.throws(TypeError, () => timeZone.toJSON());
 assert.compareArray(actual, expected);