diff --git a/src/Mailgun/Resource/Api/Domain/ConnectionResponse.php b/src/Mailgun/Resource/Api/Domain/ConnectionResponse.php
index 045ae9e..4ed4eb9 100644
--- a/src/Mailgun/Resource/Api/Domain/ConnectionResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/ConnectionResponse.php
@@ -4,12 +4,12 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
 use Mailgun\Resource\ApiResponse;
 
 /**
@@ -34,16 +34,14 @@ final class ConnectionResponse implements ApiResponse
      */
     public static function create(array $data)
     {
-        Assert::keyExists($data, 'connection');
-        Assert::isArray($data['connection']);
+        if (!isset($data['connection'])) {
+            return;
+        }
         $connSettings = $data['connection'];
 
-        Assert::keyExists($connSettings, 'skip_verification');
-        Assert::keyExists($connSettings, 'require_tls');
-
         return new self(
-            $connSettings['skip_verification'],
-            $connSettings['require_tls']
+            isset($connSettings['skip_verification']) ? $connSettings['skip_verification'] : null,
+            isset($connSettings['require_tls']) ? $connSettings['require_tls'] : null
         );
     }
 
diff --git a/src/Mailgun/Resource/Api/Domain/CreateCredentialResponse.php b/src/Mailgun/Resource/Api/Domain/CreateCredentialResponse.php
index 9b5f590..ce05897 100644
--- a/src/Mailgun/Resource/Api/Domain/CreateCredentialResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/CreateCredentialResponse.php
@@ -4,9 +4,10 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
 use Mailgun\Resource\ApiResponse;
@@ -36,7 +37,7 @@ final class CreateCredentialResponse implements ApiResponse
      */
     public static function create(array $data)
     {
-        return new self($data['message']);
+        return new self(isset($data['message']) ? $data['message'] : null);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Domain/CreateResponse.php b/src/Mailgun/Resource/Api/Domain/CreateResponse.php
index 650c644..1183a3d 100644
--- a/src/Mailgun/Resource/Api/Domain/CreateResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/CreateResponse.php
@@ -4,12 +4,12 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
 use Mailgun\Resource\ApiResponse;
 
 /**
@@ -44,23 +44,32 @@ final class CreateResponse implements ApiResponse
      */
     public static function create(array $data)
     {
-        Assert::keyExists($data, 'domain');
-        Assert::keyExists($data, 'message');
-        Assert::keyExists($data, 'receiving_dns_records');
-        Assert::keyExists($data, 'sending_dns_records');
-
-        $domain = Domain::create($data['domain']);
         $rx = [];
         $tx = [];
+        $domain = null;
+        $message = null;
 
-        foreach ($data['receiving_dns_records'] as $item) {
-            $rx[] = DnsRecord::create($item);
-        }
-        foreach ($data['sending_dns_records'] as $item) {
-            $tx[] = DnsRecord::create($item);
+        if (isset($data['domain'])) {
+            $domain = Domain::create($data['domain']);
         }
 
-        return new self($domain, $rx, $tx, $data['message']);
+        if (isset($data['message'])) {
+            $message = $data['message'];
+        }
+
+        if (isset($data['receiving_dns_records'])) {
+            foreach ($data['receiving_dns_records'] as $item) {
+                $rx[] = DnsRecord::create($item);
+            }
+        }
+
+        if (isset($data['sending_dns_records'])) {
+            foreach ($data['sending_dns_records'] as $item) {
+                $tx[] = DnsRecord::create($item);
+            }
+        }
+
+        return new self($domain, $rx, $tx, $message);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Domain/CredentialResponse.php b/src/Mailgun/Resource/Api/Domain/CredentialResponse.php
index 9212439..1a32ebc 100644
--- a/src/Mailgun/Resource/Api/Domain/CredentialResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/CredentialResponse.php
@@ -4,14 +4,13 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
 use Mailgun\Resource\ApiResponse;
-use Mailgun\Resource\Api\ErrorResponse;
 
 /**
  * @author Sean Johnson <sean@mailgun.com>
@@ -35,17 +34,20 @@ final class CredentialResponse implements ApiResponse
      */
     public static function create(array $data)
     {
-        if (array_key_exists('items', $data) && array_key_exists('total_count', $data)) {
-            $items = [];
-
+        $items = [];
+        if (isset($data['items'])) {
             foreach ($data['items'] as $item) {
                 $items[] = CredentialResponseItem::create($item);
             }
-
-            return new self($data['total_count'], $items);
-        } else {
-            return ErrorResponse::create($data);
         }
+
+        if (isset($data['total_count'])) {
+            $count = $data['total_count'];
+        } else {
+            $count = count($items);
+        }
+
+        return new self($count, $items);
     }
 
     /**
@@ -54,10 +56,6 @@ final class CredentialResponse implements ApiResponse
      */
     private function __construct($totalCount, array $items)
     {
-        Assert::integer($totalCount);
-        Assert::isArray($items);
-        Assert::allIsInstanceOf($items, 'Mailgun\Resource\Api\Domain\CredentialResponseItem');
-
         $this->totalCount = $totalCount;
         $this->items = $items;
     }
diff --git a/src/Mailgun/Resource/Api/Domain/CredentialResponseItem.php b/src/Mailgun/Resource/Api/Domain/CredentialResponseItem.php
index bd358c2..38275e2 100644
--- a/src/Mailgun/Resource/Api/Domain/CredentialResponseItem.php
+++ b/src/Mailgun/Resource/Api/Domain/CredentialResponseItem.php
@@ -4,12 +4,11 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
-namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
+namespace Mailgun\Resource\Api\Domain;
 
 /**
  * @author Sean Johnson <sean@mailgun.com>
@@ -43,26 +42,12 @@ final class CredentialResponseItem
      */
     public static function create(array $data)
     {
-        Assert::keyExists($data, 'created_at');
-        Assert::keyExists($data, 'mailbox');
-        Assert::keyExists($data, 'login');
+        $sizeBytes = isset($data['size_bytes']) ? $data['size_bytes'] : null;
+        $mailbox = isset($data['mailbox']) ? $data['mailbox'] : null;
+        $login = isset($data['login']) ? $data['login'] : null;
+        $createdAt = isset($data['created_at']) ? new \DateTime($data['created_at']) : null;
 
-        $sizeBytes = array_key_exists('size_bytes', $data) ? $data['size_bytes'] : null;
-        $createdAt = new \DateTime($data['created_at']);
-        $mailbox = $data['mailbox'];
-        $login = $data['login'];
-
-        Assert::nullOrInteger($sizeBytes);
-        Assert::isInstanceOf($createdAt, '\DateTime');
-        Assert::string($mailbox);
-        Assert::string($login);
-
-        return new self(
-            $sizeBytes,
-            $createdAt,
-            $mailbox,
-            $login
-        );
+        return new self($sizeBytes, $createdAt, $mailbox, $login);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Domain/DeleteCredentialResponse.php b/src/Mailgun/Resource/Api/Domain/DeleteCredentialResponse.php
index 730dabf..cb587eb 100644
--- a/src/Mailgun/Resource/Api/Domain/DeleteCredentialResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/DeleteCredentialResponse.php
@@ -4,9 +4,10 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
 use Mailgun\Resource\ApiResponse;
@@ -22,7 +23,7 @@ final class DeleteCredentialResponse implements ApiResponse
     private $message;
 
     /**
-     * @var error
+     * @var string
      */
     private $error;
 
@@ -33,6 +34,8 @@ final class DeleteCredentialResponse implements ApiResponse
 
     /**
      * @param string $message
+     * @param string $error
+     * @param string $spec
      */
     private function __construct($message, $error, $spec)
     {
diff --git a/src/Mailgun/Resource/Api/Domain/DnsRecord.php b/src/Mailgun/Resource/Api/Domain/DnsRecord.php
index f513ab9..6478001 100644
--- a/src/Mailgun/Resource/Api/Domain/DnsRecord.php
+++ b/src/Mailgun/Resource/Api/Domain/DnsRecord.php
@@ -4,12 +4,11 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
-namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
+namespace Mailgun\Resource\Api\Domain;
 
 /**
  * Represents a single DNS record for a domain.
@@ -52,14 +51,11 @@ final class DnsRecord
     {
         $name = isset($data['name']) ? $data['name'] : null;
         $priority = isset($data['priority']) ? $data['priority'] : null;
+        $recordType = isset($data['record_type']) ? $data['record_type'] : null;
+        $value = isset($data['value']) ? $data['value'] : null;
+        $valid = isset($data['valid']) ? $data['valid'] : null;
 
-        Assert::nullOrString($name);
-        Assert::string($data['record_type']);
-        Assert::string($data['value']);
-        Assert::nullOrString($priority);
-        Assert::string($data['valid']);
-
-        return new self($name, $data['record_type'], $data['value'], $priority, $data['valid']);
+        return new self($name, $recordType, $value, $priority, $valid);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Domain/Domain.php b/src/Mailgun/Resource/Api/Domain/Domain.php
index 53b6079..d3a0403 100644
--- a/src/Mailgun/Resource/Api/Domain/Domain.php
+++ b/src/Mailgun/Resource/Api/Domain/Domain.php
@@ -4,12 +4,11 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
-namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
+namespace Mailgun\Resource\Api\Domain;
 
 /**
  * Represents domain information in its simplest form.
@@ -60,22 +59,14 @@ final class Domain
      */
     public static function create(array $data)
     {
-        Assert::keyExists($data, 'name');
-        Assert::keyExists($data, 'smtp_login');
-        Assert::keyExists($data, 'smtp_password');
-        Assert::keyExists($data, 'wildcard');
-        Assert::keyExists($data, 'spam_action');
-        Assert::keyExists($data, 'state');
-        Assert::keyExists($data, 'created_at');
-
         return new self(
-            $data['name'],
-            $data['smtp_login'],
-            $data['smtp_password'],
-            $data['wildcard'],
-            $data['spam_action'],
-            $data['state'],
-            new \DateTime($data['created_at'])
+            isset($data['name']) ? $data['name'] : null,
+            isset($data['smtp_login']) ? $data['smtp_login'] : null,
+            isset($data['smtp_password']) ? $data['smtp_password'] : null,
+            isset($data['wildcard']) ? $data['wildcard'] : null,
+            isset($data['spam_action']) ? $data['spam_action'] : null,
+            isset($data['state']) ? $data['state'] : null,
+            isset($data['created_at']) ? new \DateTime($data['created_at']) : null
         );
     }
 
diff --git a/src/Mailgun/Resource/Api/Domain/IndexResponse.php b/src/Mailgun/Resource/Api/Domain/IndexResponse.php
index 0c36794..c5d5e20 100644
--- a/src/Mailgun/Resource/Api/Domain/IndexResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/IndexResponse.php
@@ -10,7 +10,6 @@
 
 namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
 use Mailgun\Resource\ApiResponse;
 
 /**
@@ -37,14 +36,19 @@ final class IndexResponse implements ApiResponse
     {
         $items = [];
 
-        Assert::keyExists($data, 'total_count');
-        Assert::keyExists($data, 'items');
-
-        foreach ($data['items'] as $item) {
-            $items[] = Domain::create($item);
+        if (isset($data['items'])) {
+            foreach ($data['items'] as $item) {
+                $items[] = Domain::create($item);
+            }
         }
 
-        return new self($data['total_count'], $items);
+        if (isset($data['total_count'])) {
+            $count = $data['total_count'];
+        } else {
+            $count = count($items);
+        }
+
+        return new self($count, $items);
     }
 
     /**
@@ -53,10 +57,6 @@ final class IndexResponse implements ApiResponse
      */
     private function __construct($totalCount, array $items)
     {
-        Assert::integer($totalCount);
-        Assert::isArray($items);
-        Assert::allIsInstanceOf($items, 'Mailgun\Resource\Api\Domain\Domain');
-
         $this->totalCount = $totalCount;
         $this->items = $items;
     }
diff --git a/src/Mailgun/Resource/Api/Domain/ShowResponse.php b/src/Mailgun/Resource/Api/Domain/ShowResponse.php
index da32f3a..323d7de 100644
--- a/src/Mailgun/Resource/Api/Domain/ShowResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/ShowResponse.php
@@ -4,12 +4,12 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
 use Mailgun\Resource\ApiResponse;
 
 /**
@@ -39,19 +39,24 @@ final class ShowResponse implements ApiResponse
      */
     public static function create(array $data)
     {
-        Assert::keyExists($data, 'domain');
-        Assert::keyExists($data, 'receiving_dns_records');
-        Assert::keyExists($data, 'sending_dns_records');
-
-        $domain = Domain::create($data['domain']);
         $rx = [];
         $tx = [];
+        $domain = null;
 
-        foreach ($data['receiving_dns_records'] as $item) {
-            $rx[] = DnsRecord::create($item);
+        if (isset($data['domain'])) {
+            $domain = Domain::create($data['domain']);
         }
-        foreach ($data['sending_dns_records'] as $item) {
-            $tx[] = DnsRecord::create($item);
+
+        if (isset($data['receiving_dns_records'])) {
+            foreach ($data['receiving_dns_records'] as $item) {
+                $rx[] = DnsRecord::create($item);
+            }
+        }
+
+        if (isset($data['sending_dns_records'])) {
+            foreach ($data['sending_dns_records'] as $item) {
+                $tx[] = DnsRecord::create($item);
+            }
         }
 
         return new self($domain, $rx, $tx);
diff --git a/src/Mailgun/Resource/Api/Domain/UpdateConnectionResponse.php b/src/Mailgun/Resource/Api/Domain/UpdateConnectionResponse.php
index 3354ce1..d39002e 100644
--- a/src/Mailgun/Resource/Api/Domain/UpdateConnectionResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/UpdateConnectionResponse.php
@@ -4,12 +4,12 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
-use Mailgun\Assert;
 use Mailgun\Resource\ApiResponse;
 
 /**
@@ -39,23 +39,11 @@ final class UpdateConnectionResponse implements ApiResponse
      */
     public static function create(array $data)
     {
-        Assert::keyExists($data, 'message');
-        Assert::keyExists($data, 'skip_verification');
-        Assert::keyExists($data, 'require_tls');
+        $message = isset($data['message']) ? $data['message'] : null;
+        $noVerify = isset($data['skip_verification']) ? $data['skip_verification'] : null;
+        $requireTLS = isset($data['require_tls']) ? $data['require_tls'] : null;
 
-        $message = $data['message'];
-        $noVerify = $data['skip_verification'];
-        $requireTLS = $data['require_tls'];
-
-        Assert::nullOrString($message);
-        Assert::boolean($noVerify);
-        Assert::boolean($requireTLS);
-
-        return new self(
-            $message,
-            $noVerify,
-            $requireTLS
-        );
+        return new self($message, $noVerify, $requireTLS);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Domain/UpdateCredentialResponse.php b/src/Mailgun/Resource/Api/Domain/UpdateCredentialResponse.php
index 9f7bf05..2c4ead7 100644
--- a/src/Mailgun/Resource/Api/Domain/UpdateCredentialResponse.php
+++ b/src/Mailgun/Resource/Api/Domain/UpdateCredentialResponse.php
@@ -4,9 +4,10 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Domain;
 
 use Mailgun\Resource\ApiResponse;
@@ -36,7 +37,7 @@ final class UpdateCredentialResponse implements ApiResponse
      */
     public static function create(array $data)
     {
-        return new self($data['message']);
+        return new self(isset($data['message']) ? $data['message'] : null);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/ErrorResponse.php b/src/Mailgun/Resource/Api/ErrorResponse.php
index f093e84..c759e34 100644
--- a/src/Mailgun/Resource/Api/ErrorResponse.php
+++ b/src/Mailgun/Resource/Api/ErrorResponse.php
@@ -4,9 +4,10 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api;
 
 use Mailgun\Resource\ApiResponse;
@@ -33,7 +34,7 @@ final class ErrorResponse implements ApiResponse
     }
 
     /**
-     * @param array data
+     * @param array
      *
      * @return self
      */
diff --git a/src/Mailgun/Resource/Api/Stats/AllResponse.php b/src/Mailgun/Resource/Api/Stats/AllResponse.php
index 29835d4..1065cdf 100644
--- a/src/Mailgun/Resource/Api/Stats/AllResponse.php
+++ b/src/Mailgun/Resource/Api/Stats/AllResponse.php
@@ -4,9 +4,10 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Stats;
 
 use Mailgun\Resource\ApiResponse;
@@ -44,11 +45,19 @@ final class AllResponse implements ApiResponse
     public static function create(array $data)
     {
         $items = [];
-        foreach ($data['items'] as $i) {
-            $items[] = AllResponseItem::create($i);
+        if (isset($data['items'])) {
+            foreach ($data['items'] as $i) {
+                $items[] = AllResponseItem::create($i);
+            }
         }
 
-        return new self($data['total_count'], $items);
+        if (isset($data['total_count'])) {
+            $count = $data['total_count'];
+        } else {
+            $count = count($items);
+        }
+
+        return new self($count, $items);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Stats/AllResponseItem.php b/src/Mailgun/Resource/Api/Stats/AllResponseItem.php
index ab52a05..b3c6a18 100644
--- a/src/Mailgun/Resource/Api/Stats/AllResponseItem.php
+++ b/src/Mailgun/Resource/Api/Stats/AllResponseItem.php
@@ -4,12 +4,11 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
-namespace Mailgun\Resource\Api\Stats;
 
-use Mailgun\Assert;
+namespace Mailgun\Resource\Api\Stats;
 
 /**
  * @author Tobias Nyholm <tobias.nyholm@gmail.com>
@@ -48,13 +47,13 @@ final class AllResponseItem
      */
     public static function create(array $data)
     {
-        Assert::string($data['id']);
-        Assert::string($data['event']);
-        Assert::string($data['total_count']);
-        Assert::isArray($data['tags']);
-        Assert::string($data['created_at']);
-
-        return new self($data['id'], $data['event'], $data['total_count'], $data['tags'], new \DateTime($data['created_at']));
+        return new self(
+            isset($data['id']) ? $data['id'] : null,
+            isset($data['event']) ? $data['event'] : null,
+            isset($data['total_count']) ? $data['total_count'] : null,
+            isset($data['tags']) ? $data['tags'] : null,
+            isset($data['created_at']) ? new \DateTime($data['created_at']) : null
+        );
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Stats/TotalResponse.php b/src/Mailgun/Resource/Api/Stats/TotalResponse.php
index 4b818a9..6163c1d 100644
--- a/src/Mailgun/Resource/Api/Stats/TotalResponse.php
+++ b/src/Mailgun/Resource/Api/Stats/TotalResponse.php
@@ -4,9 +4,10 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
+
 namespace Mailgun\Resource\Api\Stats;
 
 use Mailgun\Resource\ApiResponse;
@@ -58,11 +59,17 @@ final class TotalResponse implements ApiResponse
     public static function create(array $data)
     {
         $stats = [];
-        foreach ($data['stats'] as $s) {
-            $stats[] = TotalResponseItem::create($s);
+        if (isset($data['status'])) {
+            foreach ($data['stats'] as $s) {
+                $stats[] = TotalResponseItem::create($s);
+            }
         }
 
-        return new self(new \DateTime($data['start']), new \DateTime($data['end']), $data['resolution'], $stats);
+        $start = isset($data['start']) ? new \DateTime($data['start']) : null;
+        $end = isset($data['end']) ? new \DateTime($data['end']) : null;
+        $resolution = isset($data['resolution']) ? $data['resolution'] : null;
+
+        return new self($start, $end, $resolution, $stats);
     }
 
     /**
diff --git a/src/Mailgun/Resource/Api/Stats/TotalResponseItem.php b/src/Mailgun/Resource/Api/Stats/TotalResponseItem.php
index 4f0af57..f0166e7 100644
--- a/src/Mailgun/Resource/Api/Stats/TotalResponseItem.php
+++ b/src/Mailgun/Resource/Api/Stats/TotalResponseItem.php
@@ -4,12 +4,11 @@
  * Copyright (C) 2013-2016 Mailgun
  *
  * This software may be modified and distributed under the terms
- * of the MIT license.  See the LICENSE file for details.
+ * of the MIT license. See the LICENSE file for details.
  */
 
-namespace Mailgun\Resource\Api\Stats;
 
-use Mailgun\Assert;
+namespace Mailgun\Resource\Api\Stats;
 
 /**
  * @author Tobias Nyholm <tobias.nyholm@gmail.com>
@@ -43,12 +42,12 @@ class TotalResponseItem
      */
     public static function create(array $data)
     {
-        Assert::string($data['time']);
-        Assert::isArray($data['accepted']);
-        Assert::isArray($data['delivered']);
-        Assert::isArray($data['failed']);
-
-        return new self(new \DateTime($data['time']), $data['accepted'], $data['delivered'], $data['failed']);
+        return new self(
+            isset($data['time']) ? new \DateTime($data['time']) : null,
+            isset($data['accepted']) ? $data['accepted'] : null,
+            isset($data['delivered']) ? $data['delivered'] : null,
+            isset($data['failed']) ? $data['failed'] : null
+        );
     }
 
     /**