diff --git a/Form/Extension/CustomerMailMagazineTypeExtension.php b/Form/Extension/CustomerMailMagazineTypeExtension.php
index abd2e99..cf6b8aa 100644
--- a/Form/Extension/CustomerMailMagazineTypeExtension.php
+++ b/Form/Extension/CustomerMailMagazineTypeExtension.php
@@ -74,7 +74,7 @@ public function getExtendedType()
      *
      * @return string[]
      */
-    public function getExtendedTypes()
+    public static function getExtendedTypes()
     {
         yield CustomerType::class;
     }
diff --git a/Form/Extension/EntryMailMagazineTypeExtension.php b/Form/Extension/EntryMailMagazineTypeExtension.php
index 2655900..7783c91 100644
--- a/Form/Extension/EntryMailMagazineTypeExtension.php
+++ b/Form/Extension/EntryMailMagazineTypeExtension.php
@@ -95,7 +95,7 @@ public function getExtendedType()
      *
      * @return string[]
      */
-    public function getExtendedTypes()
+    public static function getExtendedTypes()
     {
         yield EntryType::class;
     }