diff --git a/spec/Packagist/Api/Result/Package/DistSpec.php b/spec/Packagist/Api/Result/Package/DistSpec.php
index d09f83e..d55ac25 100644
--- a/spec/Packagist/Api/Result/Package/DistSpec.php
+++ b/spec/Packagist/Api/Result/Package/DistSpec.php
@@ -43,4 +43,28 @@ public function it_gets_shasum()
     {
         $this->getShasum()->shouldReturn('cb0a489db41707d5df078f1f35e028e04ffd9e8e');
     }
+
+    public function it_can_deal_with_nullable_reference()
+    {
+        $this->fromArray([
+            'type'      => 'git',
+            'url'       => 'https://github.com/Sylius/Sylius.git',
+            'reference' => null,
+            'shasum'    => 'cb0a489db41707d5df078f1f35e028e04ffd9e8e',
+        ]);
+
+        $this->getReference()->shouldReturn(null);
+    }
+
+    public function it_can_deal_with_nullable_shasum()
+    {
+        $this->fromArray([
+            'type'      => 'git',
+            'url'       => 'https://github.com/Sylius/Sylius.git',
+            'reference' => 'cb0a489db41707d5df078f1f35e028e04ffd9e8e',
+            'shasum'    => null,
+        ]);
+
+        $this->getShasum()->shouldReturn(null);
+    }
 }
diff --git a/src/Packagist/Api/Result/Package/Dist.php b/src/Packagist/Api/Result/Package/Dist.php
index c85a5c4..2f9cd96 100644
--- a/src/Packagist/Api/Result/Package/Dist.php
+++ b/src/Packagist/Api/Result/Package/Dist.php
@@ -4,17 +4,19 @@
 
 namespace Packagist\Api\Result\Package;
 
-class Dist extends Source
+use Packagist\Api\Result\AbstractResult;
+
+class Dist extends AbstractResult
 {
-    protected string $shasum;
+    protected ?string $shasum;
 
     protected string $type;
 
     protected string $url;
 
-    protected string $reference;
+    protected ?string $reference;
 
-    public function getShasum(): string
+    public function getShasum(): ?string
     {
         return $this->shasum;
     }
@@ -29,7 +31,7 @@ public function getUrl(): string
         return $this->url;
     }
 
-    public function getReference(): string
+    public function getReference(): ?string
     {
         return $this->reference;
     }