diff --git a/module/Core/src/Entity/ShortUrl.php b/module/Core/src/Entity/ShortUrl.php
index 4af8844b..10df9352 100644
--- a/module/Core/src/Entity/ShortUrl.php
+++ b/module/Core/src/Entity/ShortUrl.php
@@ -32,7 +32,7 @@ class ShortUrl extends AbstractEntity
     private ?Chronos $validSince = null;
     private ?Chronos $validUntil = null;
     private ?int $maxVisits = null;
-    private ?Domain $domain;
+    private ?Domain $domain = null;
     private bool $customSlugWasProvided;
     private int $shortCodeLength;
 
diff --git a/module/Rest/src/Entity/ApiKey.php b/module/Rest/src/Entity/ApiKey.php
index f23d22e1..1d372c9c 100644
--- a/module/Rest/src/Entity/ApiKey.php
+++ b/module/Rest/src/Entity/ApiKey.php
@@ -11,7 +11,7 @@ use Shlinkio\Shlink\Common\Entity\AbstractEntity;
 class ApiKey extends AbstractEntity
 {
     private string $key;
-    private ?Chronos $expirationDate;
+    private ?Chronos $expirationDate = null;
     private bool $enabled;
 
     public function __construct(?Chronos $expirationDate = null)