diff --git a/.changeset/hip-experts-wink.md b/.changeset/hip-experts-wink.md
new file mode 100644
index 0000000..18b7d61
--- /dev/null
+++ b/.changeset/hip-experts-wink.md
@@ -0,0 +1,5 @@
+---
+"fingerprint-pro-server-api-php-sdk": patch
+---
+
+Mark nullable types as an optional, will fix #123
diff --git a/src/Model/SeenAt.php b/src/Model/SeenAt.php
index f6b4148..dcfc08f 100644
--- a/src/Model/SeenAt.php
+++ b/src/Model/SeenAt.php
@@ -202,7 +202,7 @@ public function valid(): bool
     /**
      * Gets global.
      */
-    public function getGlobal(): \DateTime
+    public function getGlobal(): ?\DateTime
     {
         return $this->container['global'];
     }
@@ -214,7 +214,7 @@ public function getGlobal(): \DateTime
      *
      * @return $this
      */
-    public function setGlobal(\DateTime $global): self
+    public function setGlobal(?\DateTime $global): self
     {
         $this->container['global'] = $global;
 
@@ -224,7 +224,7 @@ public function setGlobal(\DateTime $global): self
     /**
      * Gets subscription.
      */
-    public function getSubscription(): \DateTime
+    public function getSubscription(): ?\DateTime
     {
         return $this->container['subscription'];
     }
@@ -236,7 +236,7 @@ public function getSubscription(): \DateTime
      *
      * @return $this
      */
-    public function setSubscription(\DateTime $subscription): self
+    public function setSubscription(?\DateTime $subscription): self
     {
         $this->container['subscription'] = $subscription;
 
diff --git a/template/model_generic.mustache b/template/model_generic.mustache
index 34b3bcf..b7abd04 100644
--- a/template/model_generic.mustache
+++ b/template/model_generic.mustache
@@ -248,7 +248,7 @@ class {{classname}} {{#parentSchema}}extends {{{parent}}} {{/parentSchema}}{{^pa
      * Gets {{name}}
      * @return {{^required}}?{{/required}}{{datatype}}
      */
-    public function {{getter}}(): {{^required}}?{{/required}}{{^isListContainer}}{{^isMapContainer}}{{^isDouble}}{{datatype}}{{/isDouble}}{{/isMapContainer}}{{/isListContainer}}{{#isListContainer}}array{{/isListContainer}}{{#isMapContainer}}array{{/isMapContainer}}{{#isDouble}}float{{/isDouble}}
+    public function {{getter}}(): {{^required}}?{{/required}}{{#required}}{{#nullable}}?{{/nullable}}{{/required}}{{^isListContainer}}{{^isMapContainer}}{{^isDouble}}{{datatype}}{{/isDouble}}{{/isMapContainer}}{{/isListContainer}}{{#isListContainer}}array{{/isListContainer}}{{#isMapContainer}}array{{/isMapContainer}}{{#isDouble}}float{{/isDouble}}
     {
         return $this->container['{{name}}'];
     }
@@ -260,7 +260,7 @@ class {{classname}} {{#parentSchema}}extends {{{parent}}} {{/parentSchema}}{{^pa
      *
      * @return $this
      */
-    public function {{setter}}({{^required}}?{{/required}}{{^isListContainer}}{{^isMapContainer}}{{^isDouble}}{{datatype}}{{/isDouble}}{{/isMapContainer}}{{/isListContainer}}{{#isListContainer}}array{{/isListContainer}}{{#isMapContainer}}array{{/isMapContainer}}{{#isDouble}}float{{/isDouble}} ${{name}}): self
+    public function {{setter}}({{^required}}?{{/required}}{{#required}}{{#nullable}}?{{/nullable}}{{/required}}{{^isListContainer}}{{^isMapContainer}}{{^isDouble}}{{datatype}}{{/isDouble}}{{/isMapContainer}}{{/isListContainer}}{{#isListContainer}}array{{/isListContainer}}{{#isMapContainer}}array{{/isMapContainer}}{{#isDouble}}float{{/isDouble}} ${{name}}): self
     {
         {{#isEnum}}
         $allowedValues = $this->{{getter}}AllowableValues();
diff --git a/test/FingerprintApiTest.php b/test/FingerprintApiTest.php
index aec3f7c..48e8ac0 100644
--- a/test/FingerprintApiTest.php
+++ b/test/FingerprintApiTest.php
@@ -198,6 +198,17 @@ public function testGetEventRawResponse()
         $this->assertEquals($mockedResult, \GuzzleHttp\json_decode($response->getBody()->getContents()));
     }
 
+    public function testGetEventNullableSeenAt()
+    {
+        $this->mockHandler->reset();
+        $this->mockHandler->append($this->getMockResponse(self::MOCK_REQUEST_ID));
+
+        list($event, $response) = $this->fingerprint_api->getEvent(self::MOCK_REQUEST_ID);
+        $products = $event->getProducts();
+        $seenAt = $products->getIdentification()->getData()->getLastSeenAt();
+        $this->assertEquals(null, $seenAt->getGlobal());
+    }
+
     public function testGetVisitsRawResponse()
     {
         $this->mockHandler->reset();