diff --git a/core/modules/field/src/Tests/EntityReference/EntityReferenceItemTest.php b/core/modules/field/src/Tests/EntityReference/EntityReferenceItemTest.php
index 859551d..e75f33a 100644
--- a/core/modules/field/src/Tests/EntityReference/EntityReferenceItemTest.php
+++ b/core/modules/field/src/Tests/EntityReference/EntityReferenceItemTest.php
@@ -246,7 +246,7 @@ public function testSelectionHandlerSettings() {
     $field = FieldConfig::load($field->id());
     $this->assertTrue($field->getSetting('handler') == 'default:entity_test');
 
-    $field->settings['handler'] = 'views';
+    $field->setSetting('handler', 'views');
     $field->save();
     $field = FieldConfig::load($field->id());
     $this->assertTrue($field->getSetting('handler') == 'views');
diff --git a/core/modules/image/src/Tests/ImageFieldDisplayTest.php b/core/modules/image/src/Tests/ImageFieldDisplayTest.php
index 2679328..875a2a2 100644
--- a/core/modules/image/src/Tests/ImageFieldDisplayTest.php
+++ b/core/modules/image/src/Tests/ImageFieldDisplayTest.php
@@ -82,7 +82,7 @@ function _testImageFieldFormatters($scheme) {
 
     // After previewing, make the alt field required. It cannot be required
     // during preview because the form validation will fail.
-    $instance->settings['alt_field_required'] = 1;
+    $instance->setSetting('alt_field_required', 1);
     $instance->save();
 
     // Create alt text for the image.