diff --git a/Models/NullProfile.php b/Models/NullProfile.php
index 8531373..aee6e77 100644
--- a/Models/NullProfile.php
+++ b/Models/NullProfile.php
@@ -34,5 +34,6 @@ final class NullProfile extends Profile
     public function __construct(int $id = 0)
     {
         $this->id = $id;
+        parent::__construct();
     }
 }
diff --git a/Models/Profile.php b/Models/Profile.php
index 074fb0e..5e98655 100644
--- a/Models/Profile.php
+++ b/Models/Profile.php
@@ -50,10 +50,10 @@ class Profile implements \JsonSerializable
     /**
      * Birthday.
      *
-     * @var \DateTime
+     * @var null|\DateTime
      * @since 1.0.0
      */
-    protected \DateTime $birthday;
+    protected ?\DateTime $birthday = null;
 
     /**
      * Account.
@@ -90,7 +90,7 @@ class Profile implements \JsonSerializable
     {
         $this->image    = new NullMedia();
         $this->birthday = new \DateTime('now');
-        $this->account  = $account ?? new Account();
+        $this->account  = $account ?? new NullAccount();
     }
 
     /**
@@ -212,13 +212,13 @@ class Profile implements \JsonSerializable
     /**
      * Set birthday.
      *
-     * @param \DateTime $birthday Birthday
+     * @param null|\DateTime $birthday Birthday
      *
      * @return void
      *
      * @since 1.0.0
      */
-    public function setBirthday(\DateTime $birthday) : void
+    public function setBirthday(?\DateTime $birthday) : void
     {
         $this->birthday = $birthday;
     }
@@ -226,11 +226,11 @@ class Profile implements \JsonSerializable
     /**
      * Get birthday.
      *
-     * @return \DateTime
+     * @return null|\DateTime
      *
      * @since 1.0.0
      */
-    public function getBirthday() : \DateTime
+    public function getBirthday() : ?\DateTime
     {
         return $this->birthday;
     }
diff --git a/Theme/Backend/profile-single.tpl.php b/Theme/Backend/profile-single.tpl.php
index ceb1ad9..d54baae 100644
--- a/Theme/Backend/profile-single.tpl.php
+++ b/Theme/Backend/profile-single.tpl.php
@@ -83,7 +83,7 @@ echo $this->getData('nav')->render();
                                     <td itemprop="jobTitle">Sailor
                                 <tr>
                                     <th><?= $this->getHtml('Birthday') ?>
-                                    <td itemprop="birthDate" itemprop="foundingDate"><?= $profile->getBirthday()->format('Y-m-d'); ?>
+                                    <td itemprop="birthDate" itemprop="foundingDate"><?= $profile->getBirthday() !== null ? $profile->getBirthday()->format('Y-m-d') : ''; ?>
                                 <tr>
                                     <th><?= $this->getHtml('Email') ?>
                                     <td itemprop="email"><a href="mailto:>donald.duck@email.com<"><?= $this->printHtml($account->getEmail()); ?></a>