diff --git a/README.md b/README.md
index 09b4472..6dc2859 100644
--- a/README.md
+++ b/README.md
@@ -119,23 +119,23 @@ use Hostnet\Component\EntityRevision\RevisionInterface;
 class Revision implements RevisionInterface
 {
     #[ORM\...]
-    private $author;
+    private ?string $author;
 
     #[ORM\...]
-    private $created_at;
+    private \DateTimeInterface $created_at;
 
-    public function __construct($author, \DateTime $created_at)
+    public function __construct(?string $author, \DateTimeInterface $created_at)
     {
         $this->author     = $author;
         $this->created_at = $created_at;
     }
-    
-    public function getUser()
-    { 
+
+    public function getUser(): ?string
+    {
         return $this->author;
     }
 
-    public function getCreatedAt()
+    public function getCreatedAt(): \DateTimeInterface
     {
         return $this->created_at;
     }
@@ -188,17 +188,15 @@ The factory is responsible for providing a revision Entity. You're free to fill
 namespace Acme\Bundle\AcmeBundle;
 
 use Hostnet\Component\EntityRevision\Factory\RevisionFactoryInterface;
+use Hostnet\Component\EntityRevision\RevisionInterface;
 
 class AcmeRevisionFactory implements RevisionFactoryInterface
 {
-    private $author;
-    
-    public function __construct($author)
+    public function __construct(private string $author)
     {
-        $this->author = $author;
     }
 
-    public function createRevision(\DateTime $created_at)
+    public function createRevision(\DateTime $created_at): RevisionInterface
     {
         return new Revision($this->author, $created_at);
     }
diff --git a/UPGRADE-2.0.md b/UPGRADE-2.0.md
index 7d389d8..b484e4f 100644
--- a/UPGRADE-2.0.md
+++ b/UPGRADE-2.0.md
@@ -16,7 +16,7 @@ UPGRADE FROM 1.x to 2.0
   matching return types:
   - `RevisionableInterface::setRevision()`: `static` (now fluent, must `return $this;`)
   - `RevisionableInterface::getRevision()`: `RevisionInterface`
-  - `RevisionInterface::getUser()`: `string`
+  - `RevisionInterface::getUser()`: `?string`
   - `RevisionInterface::getCreatedAt()`: `\DateTimeInterface`
   - `RevisionFactoryInterface::createRevision()`: `RevisionInterface` (no longer
     nullable)
diff --git a/src/RevisionInterface.php b/src/RevisionInterface.php
index 42489f6..0cd1a7e 100644
--- a/src/RevisionInterface.php
+++ b/src/RevisionInterface.php
@@ -9,9 +9,9 @@
 interface RevisionInterface
 {
     /**
-     * Return the user that created the revision.
+     * Return the user that created the revision, or null if there is none.
      */
-    public function getUser(): string;
+    public function getUser(): ?string;
 
     /**
      * Return the date on which the revision was created.