diff --git a/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/ChangedTestItem.php b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/ChangedTestItem.php
index 1425588..6238356 100644
--- a/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/ChangedTestItem.php
+++ b/core/modules/system/tests/modules/entity_test/src/Plugin/Field/FieldType/ChangedTestItem.php
@@ -33,6 +33,10 @@ public function preSave() {
       // Drupal\Core\Field\Plugin\Field\FieldType\ChangedItem::preSave() we need
       // to set a real time value here.
       $this->value = time();
+
+      // And we need to round microseconds to avoid a difference of 1 second at
+      // the boundary of second.
+      $this->value += round((float) explode(' ', microtime())[0]);
     }
   }
 
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
index 66e1abb..dc1384b 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
@@ -78,7 +78,7 @@ public function testChanged() {
     // between the created time and now.
     $this->assertTrue(
       ($entity->getChangedTime() >= $entity->get('created')->value) &&
-      (($entity->getChangedTime() - $entity->get('created')->value) <= time() - REQUEST_TIME),
+      (($entity->getChangedTime() - $entity->get('created')->value) <= $this->time() - REQUEST_TIME),
       'Changed and created time of original language can be assumed to be identical.'
     );
 
@@ -306,7 +306,7 @@ public function testRevisionChanged() {
     // timestamp every time.
     $this->assertTrue(
       ($entity->getChangedTime() >= $entity->get('created')->value) &&
-      (($entity->getChangedTime() - $entity->get('created')->value) <= time() - REQUEST_TIME),
+      (($entity->getChangedTime() - $entity->get('created')->value) <= $this->time() - REQUEST_TIME),
       'Changed and created time of original language can be assumed to be identical.'
     );
 
@@ -561,4 +561,14 @@ protected function getRevisionTranslationAffectedFlag(EntityTestMulRevChanged $e
     return (bool) ($id == $entity->id());
   }
 
+  /**
+   * The time value with round microseconds.
+   *
+   * @return int
+   *   The time value with round microseconds.
+   */
+  protected function time() {
+    return time() + round((float) explode(' ', microtime())[0]);
+  }
+
 }