diff --git a/.travis.yml b/.travis.yml
index e12efbf..8bcd2c8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,7 +18,7 @@ jobs:
     - stage: "Tests"
       name: "Unit Tests"
       script: vendor/bin/phpunit -c . --coverage-clover build/logs/clover.xml
-    - script: vendor/bin/phpstan analyse src/ --level 6 --no-progress
+    - script: vendor/bin/phpstan analyse src/ --level 5 --no-progress
       name: "Static Analyser"
 
 before_script:
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..27153d5
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,3 @@
+parameters:
+    ignoreErrors:
+        - '#Unsafe usage of new static().#'
diff --git a/src/Client/BasicAuthClient.php b/src/Client/BasicAuthClient.php
index f778486..9e8eb36 100644
--- a/src/Client/BasicAuthClient.php
+++ b/src/Client/BasicAuthClient.php
@@ -40,6 +40,7 @@ class BasicAuthClient implements ClientInterface
      * @param Headers $headers
      * @param CacheInterface|null $cache
      * @param string|null $apiUri
+     * @param LoggerInterface|null $logger
      * @throws UsageException
      */
     public function __construct(
@@ -48,8 +49,8 @@ public function __construct(
         Headers $headers,
         CacheInterface $cache = null,
         $apiUri = null,
-        LoggerInterface $logger = null)
-    {
+        LoggerInterface $logger = null
+    ) {
         if (empty($apiId) || empty($apiSecret)) {
             throw new UsageException("Key and secret are required");
         }
diff --git a/src/Client/BookboonResponse.php b/src/Client/BookboonResponse.php
index eeb779b..8e52364 100644
--- a/src/Client/BookboonResponse.php
+++ b/src/Client/BookboonResponse.php
@@ -113,7 +113,7 @@ public function serialize()
      */
     public function unserialize($serialized)
     {
-        $data = unserialize($serialized, ['']);
+        $data = unserialize($serialized, ['allowed_classes' => [BookboonResponse::class]]);
         $this->body = $data['body'];
         $this->status = $data['status'];
         $this->headers = $data['headers'];
diff --git a/src/Client/ClientInterface.php b/src/Client/ClientInterface.php
index 2c77c0d..c9ba951 100644
--- a/src/Client/ClientInterface.php
+++ b/src/Client/ClientInterface.php
@@ -23,7 +23,7 @@ interface ClientInterface
     const API_HOST = 'bookboon.com';
     const API_PATH = '/api';
 
-    const VERSION = 'Bookboon-PHP/3.2';
+    const VERSION = 'Bookboon-PHP/3.3';
 
     /**
      * Prepares the call to the api and if enabled tries cache provider first for GET calls.
diff --git a/src/Client/ResponseTrait.php b/src/Client/ResponseTrait.php
index 88ba93c..8dc1dff 100644
--- a/src/Client/ResponseTrait.php
+++ b/src/Client/ResponseTrait.php
@@ -28,7 +28,7 @@ protected function handleErrorResponse(string $body, array $headers, int $status
             case 400:
             case 405:
                 $returnArray = json_decode($body, true);
-                throw new ApiSyntaxException($returnArray['message']);
+                throw new ApiSyntaxException($returnArray['message'] ?? '');
             case 401:
             case 403:
                 $returnArray = json_decode($body, true);
@@ -42,7 +42,6 @@ protected function handleErrorResponse(string $body, array $headers, int $status
             case 410:
             case 404:
                 throw new ApiNotFoundException($url);
-                break;
             default:
                 $returnArray = json_decode($body, true);
                 throw new ApiGeneralException($this->generalExceptionMessage($returnArray ?? [], $headers));
@@ -86,4 +85,4 @@ protected function getResponseHeader(array $headers, string $name) : string
     {
         return $headers[$name] ?? '';
     }
-}
\ No newline at end of file
+}
diff --git a/src/Entity/Author.php b/src/Entity/Author.php
index 1d35e08..d12cc14 100644
--- a/src/Entity/Author.php
+++ b/src/Entity/Author.php
@@ -22,12 +22,12 @@ public static function get(Bookboon $bookboon, string $authorId) : BookboonRespo
             throw new BadUUIDException();
         }
 
-        $bResponse = $bookboon->rawRequest("/authors/$authorId");
+        $bResponse = $bookboon->rawRequest("/v1/authors/$authorId");
 
         $bResponse->setEntityStore(
             new EntityStore(
                 [
-                    new static($bResponse->getReturnArray())
+                    new self($bResponse->getReturnArray())
                 ]
             )
         );
@@ -43,7 +43,7 @@ public static function get(Bookboon $bookboon, string $authorId) : BookboonRespo
      */
     public static function getAll(Bookboon $bookboon)
     {
-        $bResponse = $bookboon->rawRequest("/authors");
+        $bResponse = $bookboon->rawRequest('/v1/authors');
 
         $bResponse->setEntityStore(
             new EntityStore(static::getEntitiesFromArray($bResponse->getReturnArray()))
@@ -63,7 +63,7 @@ public static function getAll(Bookboon $bookboon)
      */
     public static function getByBookId(Bookboon $bookboon, string $bookId) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest("/books/$bookId/authors");
+        $bResponse = $bookboon->rawRequest("/v1/books/$bookId/authors");
 
         $bResponse->setEntityStore(
             new EntityStore(static::getEntitiesFromArray($bResponse->getReturnArray()))
diff --git a/src/Entity/Book.php b/src/Entity/Book.php
index f74817d..5540697 100644
--- a/src/Entity/Book.php
+++ b/src/Entity/Book.php
@@ -32,7 +32,7 @@ abstract class Book extends Entity
      */
     public static function get(Bookboon $bookboon, string $bookId, bool $extendedMetadata = false) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest("/books/$bookId", ['extendedMetadata' => $extendedMetadata ? 'true' : 'false']);
+        $bResponse = $bookboon->rawRequest("/v1/books/$bookId", ['extendedMetadata' => $extendedMetadata ? 'true' : 'false']);
 
         $bResponse->setEntityStore(
             new EntityStore(
@@ -69,7 +69,7 @@ public static function getMultiple(
             'extendedMetadata' => $extendedMetadata ? 'true' : 'false'
         ];
 
-        $bResponse = $bookboon->rawRequest("/books", $variables);
+        $bResponse = $bookboon->rawRequest('/v1/books', $variables);
 
         $bResponse->setEntityStore(
             new EntityStore(static::getEntitiesFromArray($bResponse->getReturnArray()))
@@ -99,7 +99,7 @@ public static function getAll(
             'extendedMetadata' => $extendedMetadata ? 'true' : 'false'
         ];
 
-        $bResponse = $bookboon->rawRequest("/books", $variables);
+        $bResponse = $bookboon->rawRequest('/v1/books', $variables);
 
         $bResponse->setEntityStore(
             new EntityStore(static::getEntitiesFromArray($bResponse->getReturnArray()))
@@ -157,7 +157,7 @@ public static function getDownloadUrl(
     ) : string {
         $variables['format'] = $format;
 
-        $bResponse = $bookboon->rawRequest("/books/$bookId/download", $variables, ClientInterface::HTTP_POST);
+        $bResponse = $bookboon->rawRequest("/v1/books/$bookId/download", $variables, ClientInterface::HTTP_POST);
 
         return $bResponse->getReturnArray()['url'];
     }
@@ -181,7 +181,7 @@ public static function search(
         int $offset = 0,
          array $bookTypes = ['pdf']
     ) : BookboonResponse {
-        $bResponse = $bookboon->rawRequest('/search', ['q' => $query, 'limit' => $limit, 'offset' => $offset, 'bookType' => join(',', $bookTypes)]);
+        $bResponse = $bookboon->rawRequest('/v1/search', ['q' => $query, 'limit' => $limit, 'offset' => $offset, 'bookType' => join(',', $bookTypes)]);
 
         $bResponse->setEntityStore(
             new EntityStore(Book::getEntitiesFromArray($bResponse->getReturnArray()))
@@ -206,7 +206,7 @@ public static function recommendations(
         int $limit = 5,
         array $bookTypes = ['pdf']
     ) : BookboonResponse {
-        $bResponse = $bookboon->rawRequest('/recommendations', ['limit' => $limit, 'books' => $bookIds, 'bookType' => join(',', $bookTypes)]);
+        $bResponse = $bookboon->rawRequest('/v1/recommendations', ['limit' => $limit, 'books' => $bookIds, 'bookType' => join(',', $bookTypes)]);
 
         $bResponse->setEntityStore(
             new EntityStore(Book::getEntitiesFromArray($bResponse->getReturnArray()))
diff --git a/src/Entity/Category.php b/src/Entity/Category.php
index b9229c6..b35b9c8 100644
--- a/src/Entity/Category.php
+++ b/src/Entity/Category.php
@@ -8,9 +8,6 @@
 
 class Category extends Entity
 {
-    const TEXTBOOKS = 'd1fabb36-4eff-4760-a80d-a15700efa9ae';
-    const BUSINESS = '82403e77-ccbf-4e10-875c-a15700ef8a56';
-
     /**
      * Get Category.
      *
@@ -24,12 +21,12 @@ class Category extends Entity
      */
     public static function get(Bookboon $bookboon, string $categoryId, array $bookTypes = ['pdf']) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest("/categories/$categoryId", ['bookType' => join(',', $bookTypes)]);
+        $bResponse = $bookboon->rawRequest("/v1/categories/$categoryId", ['bookType' => join(',', $bookTypes)]);
 
         $bResponse->setEntityStore(
             new EntityStore(
                 [
-                    new static($bResponse->getReturnArray())
+                    new self($bResponse->getReturnArray())
                 ]
             )
         );
@@ -51,7 +48,7 @@ public static function getTree(
         array $blacklistedCategoryIds = [],
         int $depth = 2
     ) : BookboonResponse {
-        $bResponse = $bookboon->rawRequest('/categories', ['depth' => $depth]);
+        $bResponse = $bookboon->rawRequest('/v1/categories');
 
         $categories = $bResponse->getReturnArray();
 
@@ -60,7 +57,7 @@ public static function getTree(
         }
 
         $bResponse->setEntityStore(
-            new EntityStore(Category::getEntitiesFromArray($categories))
+            new EntityStore(self::getEntitiesFromArray($categories))
         );
 
         return $bResponse;
@@ -100,7 +97,7 @@ private static function recursiveBlacklist(array &$categories, array $blackliste
      */
     public static function getDownloadUrl(Bookboon $bookboon, string $categoryId, array $variables) : string
     {
-        $bResponse = $bookboon->rawRequest("/categories/$categoryId/download", $variables, ClientInterface::HTTP_POST);
+        $bResponse = $bookboon->rawRequest("/v1/categories/$categoryId/download", $variables, ClientInterface::HTTP_POST);
 
         return $bResponse->getReturnArray()['url'];
     }
diff --git a/src/Entity/Exam.php b/src/Entity/Exam.php
index fafdbb2..a102c4c 100644
--- a/src/Entity/Exam.php
+++ b/src/Entity/Exam.php
@@ -25,12 +25,12 @@ public static function get(Bookboon $bookboon, string $examId) : BookboonRespons
             throw new BadUUIDException();
         }
 
-        $bResponse = $bookboon->rawRequest("/exams/$examId");
+        $bResponse = $bookboon->rawRequest("/v1/exams/$examId");
 
         $bResponse->setEntityStore(
             new EntityStore(
                 [
-                    new static($bResponse->getReturnArray())
+                    new self($bResponse->getReturnArray())
                 ]
             )
         );
@@ -46,7 +46,7 @@ public static function get(Bookboon $bookboon, string $examId) : BookboonRespons
      */
     public static function getByBookId(Bookboon $bookboon, string $bookId) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest("/books/$bookId/exams");
+        $bResponse = $bookboon->rawRequest("/v1/books/$bookId/exams");
 
         $bResponse->setEntityStore(
             new EntityStore(Exam::getEntitiesFromArray($bResponse->getReturnArray()))
@@ -64,7 +64,7 @@ public static function getByBookId(Bookboon $bookboon, string $bookId) : Bookboo
      */
     public static function getAll(Bookboon $bookboon) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest("/exams");
+        $bResponse = $bookboon->rawRequest("/v1/exams");
 
         $bResponse->setEntityStore(
             new EntityStore(static::getEntitiesFromArray($bResponse->getReturnArray()))
@@ -75,12 +75,12 @@ public static function getAll(Bookboon $bookboon) : BookboonResponse
 
     public static function start(Bookboon $bookboon, $examId)
     {
-        return $bookboon->rawRequest("/exams/$examId", [], ClientInterface::HTTP_POST)->getReturnArray();
+        return $bookboon->rawRequest("/v1/exams/$examId", [], ClientInterface::HTTP_POST)->getReturnArray();
     }
 
     public static function finish(Bookboon $bookboon, $examId, $postVars)
     {
-        return $bookboon->rawRequest("/exams/$examId/submit", $postVars, ClientInterface::HTTP_POST)->getReturnArray();
+        return $bookboon->rawRequest("/v1/exams/$examId/submit", $postVars, ClientInterface::HTTP_POST)->getReturnArray();
     }
 
     /**
@@ -141,4 +141,4 @@ public function getQuestions()
     {
         return ExamQuestion::getEntitiesFromArray($this->safeGet('questions'));
     }
-}
\ No newline at end of file
+}
diff --git a/src/Entity/Frontpage.php b/src/Entity/Frontpage.php
index dd3a496..c0ac7d8 100644
--- a/src/Entity/Frontpage.php
+++ b/src/Entity/Frontpage.php
@@ -24,10 +24,10 @@ class Frontpage extends Entity
      */
     public static function get(Bookboon $bookboon, array $bookTypes = ['pdf']) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest('/frontpage', ['bookType' => implode(',', $bookTypes)]);
+        $bResponse = $bookboon->rawRequest('/v1/frontpage', ['bookType' => implode(',', $bookTypes)]);
 
         $bResponse->setEntityStore(
-            new EntityStore(Frontpage::getEntitiesFromArray($bResponse->getReturnArray()))
+            new EntityStore(self::getEntitiesFromArray($bResponse->getReturnArray()))
         );
 
         return $bResponse;
@@ -46,14 +46,12 @@ public static function get(Bookboon $bookboon, array $bookTypes = ['pdf']) : Boo
      */
     public static function getBySlug(Bookboon $bookboon, string $slug, array $bookTypes = ['pdf']) : BookboonResponse
     {
-
-        /** @var Frontpage[] $frontpageArray */
-        $bResponse = $bookboon->rawRequest("/frontpage/$slug", ['bookType' => join(',', $bookTypes)]);
+        $bResponse = $bookboon->rawRequest("/v1/frontpage/$slug", ['bookType' => join(',', $bookTypes)]);
 
         $bResponse->setEntityStore(
             new EntityStore(
                 [
-                    new static($bResponse->getReturnArray())
+                    new self($bResponse->getReturnArray())
                 ]
             )
         );
diff --git a/src/Entity/Journey.php b/src/Entity/Journey.php
index c8678d5..df7d434 100644
--- a/src/Entity/Journey.php
+++ b/src/Entity/Journey.php
@@ -18,9 +18,9 @@ class Journey extends Entity
      */
     public static function get(Bookboon $bookboon, string $journeyId) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest("/journeys/$journeyId");
+        $bResponse = $bookboon->rawRequest("/v1/journeys/$journeyId");
 
-        $journeyEntity = new static($bResponse->getReturnArray());
+        $journeyEntity = new self($bResponse->getReturnArray());
 
         if (count($journeyEntity->getBookIds()) > 0) {
             $books = Book::getMultiple($bookboon, $journeyEntity->getBookIds(), false);
@@ -49,7 +49,7 @@ public static function get(Bookboon $bookboon, string $journeyId) : BookboonResp
      */
     public static function getAll(Bookboon $bookboon, array $bookTypes = ['pdf']) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest('/journeys');
+        $bResponse = $bookboon->rawRequest('/v1/journeys');
 
         $bResponse->setEntityStore(
             new EntityStore(Journey::getEntitiesFromArray($bResponse->getReturnArray()))
diff --git a/src/Entity/Language.php b/src/Entity/Language.php
index 1c0dbdf..cf5d2e1 100644
--- a/src/Entity/Language.php
+++ b/src/Entity/Language.php
@@ -19,7 +19,7 @@ class Language extends Entity
      */
     public static function get(Bookboon $bookboon, array $bookTypes = ['pdf']) : BookboonResponse
     {
-        $bResponse = $bookboon->rawRequest('/languages');
+        $bResponse = $bookboon->rawRequest('/v1/languages');
 
         $bResponse->setEntityStore(
             new EntityStore(Language::getEntitiesFromArray($bResponse->getReturnArray()))
diff --git a/src/Entity/Question.php b/src/Entity/Question.php
index a3b0885..fbfd16d 100644
--- a/src/Entity/Question.php
+++ b/src/Entity/Question.php
@@ -22,7 +22,7 @@ public static function get(
         array $answerIds = [],
         string $rootSegmentId = ''
     ) : BookboonResponse {
-        $url = $rootSegmentId == '' ? '/questions' : '/questions/' . $rootSegmentId;
+        $url = $rootSegmentId == '' ? '/v1/questions' : '/v1/questions/' . $rootSegmentId;
         $bResponse =  $bookboon->rawRequest($url, ['answer' => $answerIds]);
 
         $bResponse->setEntityStore(
@@ -46,7 +46,7 @@ public static function send(
         array $variables = [],
         string $rootSegmentId = ''
     ) : BookboonResponse {
-        $url = $rootSegmentId == '' ? '/questions' : '/questions/' . $rootSegmentId;
+        $url = $rootSegmentId == '' ? '/v1/questions' : '/v1/questions/' . $rootSegmentId;
         $bResponse = $bookboon->rawRequest($url, $variables, ClientInterface::HTTP_POST);
         return $bResponse;
     }
diff --git a/src/Entity/Review.php b/src/Entity/Review.php
index cf3531c..ce9bf60 100644
--- a/src/Entity/Review.php
+++ b/src/Entity/Review.php
@@ -25,10 +25,10 @@ public static function getByBookId(Bookboon $bookboon, string $bookId) : Bookboo
             throw new BadUUIDException();
         }
 
-        $bResponse = $bookboon->rawRequest("/books/$bookId/review");
+        $bResponse = $bookboon->rawRequest("/v1/books/$bookId/reviews");
 
         $bResponse->setEntityStore(
-            new EntityStore(Review::getEntitiesFromArray($bResponse->getReturnArray()))
+            new EntityStore(self::getEntitiesFromArray($bResponse->getReturnArray()))
         );
 
         return $bResponse;
@@ -36,12 +36,12 @@ public static function getByBookId(Bookboon $bookboon, string $bookId) : Bookboo
 
     /**
      * @param array $review
-     * @return static
+     * @return Review
      * @throws \Bookboon\Api\Exception\EntityDataException
      */
     public static function create(array $review = []) : Review
     {
-        return new static($review);
+        return new self($review);
     }
 
 
@@ -57,7 +57,7 @@ public static function create(array $review = []) : Review
     public function submit(Bookboon $bookboon, string $bookId) : void
     {
         if (Entity::isValidUUID($bookId)) {
-            $bookboon->rawRequest("/books/$bookId/review", $this->getData(), ClientInterface::HTTP_POST);
+            $bookboon->rawRequest("/v1/books/$bookId/reviews", $this->getData(), ClientInterface::HTTP_POST);
         }
     }
 
diff --git a/src/Entity/Subscription.php b/src/Entity/Subscription.php
index e1d4231..6471f85 100644
--- a/src/Entity/Subscription.php
+++ b/src/Entity/Subscription.php
@@ -41,7 +41,7 @@ public static function add(Bookboon $bookboon, string $email, bool $hasConsented
 
         try {
             $bookboon->rawRequest(
-                '/subscriptions',
+                '/v1/subscriptions',
                 $options,
                 ClientInterface::HTTP_POST,
                 false
@@ -73,7 +73,7 @@ public static function remove(Bookboon $bookboon, string $email, ?string $alias)
 
         try {
             $bookboon->rawRequest(
-                '/subscriptions',
+                '/v1/subscriptions',
                 $options,
                 ClientInterface::HTTP_DELETE,
                 false
diff --git a/tests/BookboonTest.php b/tests/BookboonTest.php
index 5a8bd8e..d066a51 100644
--- a/tests/BookboonTest.php
+++ b/tests/BookboonTest.php
@@ -33,7 +33,7 @@ public function testBadUrl()
      */
     public function testBadRequest()
     {
-        self::$bookboon->rawRequest('/search', ['get' => ['q' => '']]);
+        self::$bookboon->rawRequest('/v1/search', ['get' => ['q' => '']]);
     }
 
     /**
@@ -41,7 +41,7 @@ public function testBadRequest()
      */
     public function testNotFound()
     {
-        self::$bookboon->rawRequest('/bah');
+        self::$bookboon->rawRequest('/v1/bah');
     }
 
     /**
@@ -50,7 +50,7 @@ public function testNotFound()
     public function testBadAuthentication()
     {
         $bookboon = Bookboon::create("bad", "auth", ['basic']);
-        $bookboon->rawRequest('/categories/062adfac-844b-4e8c-9242-a1620108325e');
+        $bookboon->rawRequest('/v1/categories/062adfac-844b-4e8c-9242-a1620108325e');
     }
 
     /**
@@ -59,7 +59,7 @@ public function testBadAuthentication()
     public function testEmpty()
     {
         $bookboon = Bookboon::create("", "", ['basic']);
-        $bookboon->rawRequest('/categories/062adfac-844b-4e8c-9242-a1620108325e');
+        $bookboon->rawRequest('/v1/categories/062adfac-844b-4e8c-9242-a1620108325e');
     }
 
     public function testGetClient()
diff --git a/tests/Client/BasicAuthClientTest.php b/tests/Client/BasicAuthClientTest.php
index bf57551..8789cdf 100644
--- a/tests/Client/BasicAuthClientTest.php
+++ b/tests/Client/BasicAuthClientTest.php
@@ -36,7 +36,7 @@ public function testBadAuthentication()
         $client = new BasicAuthClient("bad", "auth", new Headers(), null);
         $bookboon = new Bookboon($client);
 
-        $bookboon->rawRequest('/categories');
+        $bookboon->rawRequest('/v1/categories');
     }
 
     public function testNonExistingHeader()
diff --git a/tests/Entity/AuthorTest.php b/tests/Entity/AuthorTest.php
index 1432bc3..9a72474 100644
--- a/tests/Entity/AuthorTest.php
+++ b/tests/Entity/AuthorTest.php
@@ -4,6 +4,7 @@
 
 use Bookboon\Api\Bookboon;
 use PHPUnit\Framework\TestCase;
+use Bookboon\Api\Entity\Book;
 
 /**
  * Class AuthorTest
@@ -19,7 +20,7 @@ public static function setUpBeforeClass()
     {
         include_once(__DIR__ . '/../Helpers.php');
         $bookboon = \Helpers::getBookboon();
-        self::$data = Author::get($bookboon, '0908031c-ce02-9b86-11e6-6dd9aa4699d1')
+        self::$data = Author::get($bookboon, '0908031c-ce02-9b86-11e6-6dd9268599d1')
             ->getEntityStore()
             ->getSingle();
     }
@@ -44,7 +45,7 @@ public function testNotFalse($method)
     public function testHasBooks()
     {
         $books = self::$data->getBooks();
-        $this->assertInstanceOf('\Bookboon\Api\Entity\Book', $books[0]);
+        $this->assertInstanceOf(Book::class, $books[0]);
     }
 
     /**
diff --git a/tests/Entity/CategoryTest.php b/tests/Entity/CategoryTest.php
index 7d9df95..3772405 100644
--- a/tests/Entity/CategoryTest.php
+++ b/tests/Entity/CategoryTest.php
@@ -59,14 +59,22 @@ public function testInvalidCategory()
     public function testGetCategoryTree()
     {
         $categories = Category::getTree(self::$bookboon)->getEntityStore()->get();
-        $this->assertEquals(2, count($categories));
+        $this->assertGreaterThan(10, count($categories));
     }
 
     public function testGetCategoryTreeBlacklist()
     {
-        $categories = Category::getTree(self::$bookboon, ['82403e77-ccbf-4e10-875c-a15700ef8a56', '07651831-1c44-4815-87a2-a2b500f5934a']);
+        $hiddenId = 'a382f37c-dc28-400a-9838-a17700ad5472';
+        $categories = Category::getTree(self::$bookboon, [$hiddenId]);
 
-        $this->assertEquals(1, count($categories->getEntityStore()->get()));
+        $categoryIds = array_map(
+            static function (Category $item) {
+                return $item->getId();
+            },
+            $categories->getEntityStore()->get()
+        );
+
+        $this->assertNotContains($hiddenId, $categoryIds);
     }
 
     public function testCategoryDownload()
diff --git a/tests/Helpers.php b/tests/Helpers.php
index 5f505aa..1d3bbc7 100644
--- a/tests/Helpers.php
+++ b/tests/Helpers.php
@@ -18,7 +18,7 @@ public static function getApiSecret()
 
     public static function getBookboon()
     {
-        $bookboon = Bookboon::create(self::getApiId(), self::getApiSecret(), ['basic', 'download_book.pdf', 'download_category']);
+        $bookboon = Bookboon::create(self::getApiId(), self::getApiSecret(), ['basic', 'api.book.academic', 'api.book.professional', 'api.download_category', 'api.journeys']);
         $bookboon->getClient()->requestAccessToken([], OauthGrants::CLIENT_CREDENTIALS);
 
         return $bookboon;
@@ -41,4 +41,4 @@ public static function invokeMethod(&$object, $methodName, array $parameters = [
 
         return $method->invokeArgs($object, $parameters);
     }
-}
\ No newline at end of file
+}