diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-noniso.js b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-noniso.js
index 326aed7c76..548a9378a6 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-noniso.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-noniso.js
@@ -10,6 +10,8 @@ includes: [temporalHelpers.js]
 
 const cal = {
   id: 'thisisnotiso',
+  era() { return undefined; },
+  eraYear() { return undefined; },
   toString() { return "this is a string"; },
   year() { return 2008; },
   month() { return 9; },
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-id.js b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-id.js
index 5c7536640b..7abc86730e 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-id.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-id.js
@@ -13,6 +13,8 @@ const cal1 = {
 };
 const cal2 = {
   id: 'thisisnotiso',
+  era() { return undefined; },
+  eraYear() { return undefined; },
   toString() { return "this is a string"; },
   year() { return 2008; },
   month() { return 9; },
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-object.js b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-object.js
index 9eaba18a94..bfe7f3755c 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-object.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar-same-object.js
@@ -11,6 +11,8 @@ includes: [temporalHelpers.js]
 let calls = 0;
 const cal = {
   id: 'thisisnotiso',
+  era() { return undefined; },
+  eraYear() { return undefined; },
   toString() {
     ++calls;
     return "this is a string";
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar.js b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar.js
index 12a28cb78e..58864db07d 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-plaindate-calendar.js
@@ -10,6 +10,8 @@ includes: [temporalHelpers.js]
 
 const cal = {
   id: 'thisisnotiso',
+  era() { return undefined; },
+  eraYear() { return undefined; },
   toString() { return "this is a string"; },
   year() { return 2008; },
   month() { return 9; },
diff --git a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-string-iso-calendar.js b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-string-iso-calendar.js
index f587118608..45e3d8bf07 100644
--- a/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-string-iso-calendar.js
+++ b/test/built-ins/Temporal/PlainDateTime/prototype/withPlainDate/argument-string-iso-calendar.js
@@ -10,6 +10,8 @@ includes: [temporalHelpers.js]
 
 const cal = {
   id: "thisisnotiso",
+  era() { return undefined; },
+  eraYear() { return undefined; },
   toString() { return "this is a string"; },
   year() { return 2008; },
   month() { return 9; },