diff --git a/tests/system/I18n/TimeLegacyTest.php b/tests/system/I18n/TimeLegacyTest.php
index 36907988349d..5814683ba6c7 100644
--- a/tests/system/I18n/TimeLegacyTest.php
+++ b/tests/system/I18n/TimeLegacyTest.php
@@ -399,10 +399,15 @@ public function testGetTimestamp(): void
 
     public function testGetAge(): void
     {
+        // setTestNow() does not work to parse().
         $time = TimeLegacy::parse('5 years ago');
 
-        $this->assertSame(5, $time->getAge());
-        $this->assertSame(5, $time->age);
+        // Considers leap year
+        $now      = TimeLegacy::now();
+        $expected = ($now->day === '29' && $now->month === '2') ? 4 : 5;
+
+        $this->assertSame($expected, $time->getAge());
+        $this->assertSame($expected, $time->age);
     }
 
     public function testAgeNow(): void
@@ -414,7 +419,7 @@ public function testAgeNow(): void
 
     public function testAgeFuture(): void
     {
-        TimeLegacy::setTestNow('June 20, 2022', 'America/Chicago');
+        TimeLegacy::setTestNow('June 20, 2022');
         $time = TimeLegacy::parse('August 12, 2116 4:15:23pm');
 
         $this->assertSame(0, $time->getAge());
@@ -422,7 +427,7 @@ public function testAgeFuture(): void
 
     public function testGetAgeSameDayOfBirthday(): void
     {
-        TimeLegacy::setTestNow('December 31, 2022', 'America/Chicago');
+        TimeLegacy::setTestNow('December 31, 2022');
         $time = TimeLegacy::parse('December 31, 2020');
 
         $this->assertSame(2, $time->getAge());
@@ -430,7 +435,7 @@ public function testGetAgeSameDayOfBirthday(): void
 
     public function testGetAgeNextDayOfBirthday(): void
     {
-        TimeLegacy::setTestNow('January 1, 2022', 'America/Chicago');
+        TimeLegacy::setTestNow('January 1, 2022');
         $time = TimeLegacy::parse('December 31, 2020');
 
         $this->assertSame(1, $time->getAge());
@@ -438,7 +443,7 @@ public function testGetAgeNextDayOfBirthday(): void
 
     public function testGetAgeBeforeDayOfBirthday(): void
     {
-        TimeLegacy::setTestNow('December 30, 2021', 'America/Chicago');
+        TimeLegacy::setTestNow('December 30, 2021');
         $time = TimeLegacy::parse('December 31, 2020');
 
         $this->assertSame(0, $time->getAge());
diff --git a/tests/system/I18n/TimeTest.php b/tests/system/I18n/TimeTest.php
index d60fb4410a03..db34590eadeb 100644
--- a/tests/system/I18n/TimeTest.php
+++ b/tests/system/I18n/TimeTest.php
@@ -406,10 +406,15 @@ public function testGetTimestamp(): void
      */
     public function testGetAge(): void
     {
+        // setTestNow() does not work to parse().
         $time = Time::parse('5 years ago');
 
-        $this->assertSame(5, $time->getAge());
-        $this->assertSame(5, $time->age);
+        // Considers leap year
+        $now      = Time::now();
+        $expected = ($now->day === '29' && $now->month === '2') ? 4 : 5;
+
+        $this->assertSame($expected, $time->getAge());
+        $this->assertSame($expected, $time->age);
     }
 
     public function testAgeNow(): void
@@ -421,7 +426,7 @@ public function testAgeNow(): void
 
     public function testAgeFuture(): void
     {
-        Time::setTestNow('June 20, 2022', 'America/Chicago');
+        Time::setTestNow('June 20, 2022');
         $time = Time::parse('August 12, 2116 4:15:23pm');
 
         $this->assertSame(0, $time->getAge());
@@ -429,7 +434,7 @@ public function testAgeFuture(): void
 
     public function testGetAgeSameDayOfBirthday(): void
     {
-        Time::setTestNow('December 31, 2022', 'America/Chicago');
+        Time::setTestNow('December 31, 2022');
         $time = Time::parse('December 31, 2020');
 
         $this->assertSame(2, $time->getAge());
@@ -437,7 +442,7 @@ public function testGetAgeSameDayOfBirthday(): void
 
     public function testGetAgeNextDayOfBirthday(): void
     {
-        Time::setTestNow('January 1, 2022', 'America/Chicago');
+        Time::setTestNow('January 1, 2022');
         $time = Time::parse('December 31, 2020');
 
         $this->assertSame(1, $time->getAge());
@@ -445,7 +450,7 @@ public function testGetAgeNextDayOfBirthday(): void
 
     public function testGetAgeBeforeDayOfBirthday(): void
     {
-        Time::setTestNow('December 30, 2021', 'America/Chicago');
+        Time::setTestNow('December 30, 2021');
         $time = Time::parse('December 31, 2020');
 
         $this->assertSame(0, $time->getAge());