diff --git a/modules/mailchimp_lists/src/Form/MailchimpListsSubscribeForm.php b/modules/mailchimp_lists/src/Form/MailchimpListsSubscribeForm.php
index f836215..9c44df3 100644
--- a/modules/mailchimp_lists/src/Form/MailchimpListsSubscribeForm.php
+++ b/modules/mailchimp_lists/src/Form/MailchimpListsSubscribeForm.php
@@ -143,10 +143,6 @@ class MailchimpListsSubscribeForm extends FormBase {
 
         $groups_default = $this->fieldInstance->getInterestGroups();
 
-        if ($groups_default == NULL) {
-          $groups_default = [];
-        }
-
         $form[$wrapper_key]['interest_groups'] += mailchimp_interest_groups_form_elements($mc_list, $groups_default, $email);
       }
     }
diff --git a/modules/mailchimp_lists/src/Plugin/Field/FieldType/MailchimpListsSubscription.php b/modules/mailchimp_lists/src/Plugin/Field/FieldType/MailchimpListsSubscription.php
index 9d8de53..06ca204 100644
--- a/modules/mailchimp_lists/src/Plugin/Field/FieldType/MailchimpListsSubscription.php
+++ b/modules/mailchimp_lists/src/Plugin/Field/FieldType/MailchimpListsSubscription.php
@@ -294,11 +294,7 @@ class MailchimpListsSubscription extends FieldItemBase {
    *   The field 'interest_groups' value.
    */
   public function getInterestGroups() {
-    if (isset($this->values['interest_groups'])) {
-      return $this->values['interest_groups'];
-    }
-
-    return NULL;
+    return $this->values['interest_groups'] ?? [];
   }
 
   /**
diff --git a/modules/mailchimp_lists/src/Plugin/Field/FieldWidget/MailchimpListsSelectWidget.php b/modules/mailchimp_lists/src/Plugin/Field/FieldWidget/MailchimpListsSelectWidget.php
index 78945ed..8a0df48 100644
--- a/modules/mailchimp_lists/src/Plugin/Field/FieldWidget/MailchimpListsSelectWidget.php
+++ b/modules/mailchimp_lists/src/Plugin/Field/FieldWidget/MailchimpListsSelectWidget.php
@@ -255,9 +255,6 @@ class MailchimpListsSelectWidget extends WidgetBase {
   protected function getInterestGroupsDefaults($instance) {
     $groups_default = $instance->getInterestGroups();
 
-    if ($groups_default == NULL) {
-      $groups_default = [];
-    }
     return $groups_default;
   }