diff --git a/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php b/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php
index 8d50c22..ea9e0c8 100644
--- a/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php
+++ b/core/modules/field/tests/src/Unit/FieldUninstallValidatorTest.php
@@ -53,7 +53,9 @@ public function testValidateDeleted() {
     $field_storage = $this->getMockBuilder('Drupal\field\Entity\FieldStorageConfig')
       ->disableOriginalConstructor()
       ->getMock();
-    $field_storage->deleted = TRUE;
+    $field_storage->expects($this->once())
+      ->method('isDeleted')
+      ->willReturn(TRUE);
     $this->fieldUninstallValidator->expects($this->once())
       ->method('getFieldStoragesByModule')
       ->willReturn([$field_storage]);
@@ -71,7 +73,9 @@ public function testValidateNoDeleted() {
     $field_storage = $this->getMockBuilder('Drupal\field\Entity\FieldStorageConfig')
       ->disableOriginalConstructor()
       ->getMock();
-    $field_storage->deleted = FALSE;
+    $field_storage->expects($this->once())
+      ->method('isDeleted')
+      ->willReturn(FALSE);
     $this->fieldUninstallValidator->expects($this->once())
       ->method('getFieldStoragesByModule')
       ->willReturn([$field_storage]);