diff --git a/phpstan.neon b/phpstan.neon
index b4dfad5c..1c1d972a 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,5 +1,5 @@
 parameters:
-	level: 4
+	level: 5
 	paths:
 		- app
 		- src
diff --git a/src/ElasticSearch/Aggregation/Bucket.php b/src/ElasticSearch/Aggregation/Bucket.php
index eb2027ff..0ab19670 100644
--- a/src/ElasticSearch/Aggregation/Bucket.php
+++ b/src/ElasticSearch/Aggregation/Bucket.php
@@ -4,28 +4,14 @@
 
 namespace CultuurNet\UDB3\Search\ElasticSearch\Aggregation;
 
-use InvalidArgumentException;
-
 final class Bucket
 {
     private string $key;
 
     private int $count;
 
-    /**
-     * @param string $key
-     * @param int $count
-     */
-    public function __construct($key, $count)
+    public function __construct(string $key, int $count)
     {
-        if (!is_string($key)) {
-            throw new InvalidArgumentException('Bucket key should be a string.');
-        }
-
-        if (!is_int($count)) {
-            throw new InvalidArgumentException('Bucket count should be an int.');
-        }
-
         $this->key = $key;
         $this->count = $count;
     }
diff --git a/src/Http/Organizer/RequestParser/CompositeOrganizerRequestParser.php b/src/Http/Organizer/RequestParser/CompositeOrganizerRequestParser.php
index 79d422f6..72fc594b 100644
--- a/src/Http/Organizer/RequestParser/CompositeOrganizerRequestParser.php
+++ b/src/Http/Organizer/RequestParser/CompositeOrganizerRequestParser.php
@@ -4,8 +4,8 @@
 
 namespace CultuurNet\UDB3\Search\Http\Organizer\RequestParser;
 
+use CultuurNet\UDB3\Search\Http\ApiRequestInterface;
 use CultuurNet\UDB3\Search\Organizer\OrganizerQueryBuilderInterface;
-use Psr\Http\Message\ServerRequestInterface;
 
 final class CompositeOrganizerRequestParser implements OrganizerRequestParser
 {
@@ -27,7 +27,7 @@ public function withParser(OrganizerRequestParser $parser): self
     }
 
     public function parse(
-        ServerRequestInterface $request,
+        ApiRequestInterface $request,
         OrganizerQueryBuilderInterface $organizerQueryBuilder
     ): OrganizerQueryBuilderInterface {
         foreach ($this->parsers as $parser) {
diff --git a/src/PagedResultSet.php b/src/PagedResultSet.php
index 730b02a4..aa2ec763 100644
--- a/src/PagedResultSet.php
+++ b/src/PagedResultSet.php
@@ -4,8 +4,8 @@
 
 namespace CultuurNet\UDB3\Search;
 
+use CultuurNet\UDB3\Search\Facet\FacetTreeInterface;
 use InvalidArgumentException;
-use CultuurNet\UDB3\Search\Facet\FacetFilter;
 use CultuurNet\UDB3\Search\ReadModel\JsonDocument;
 
 final class PagedResultSet
@@ -20,7 +20,7 @@ final class PagedResultSet
     private array $results;
 
     /**
-     * @var FacetFilter[]
+     * @var FacetTreeInterface[]
      */
     private $facets;
 
@@ -55,7 +55,7 @@ public function getResults(): array
         return $this->results;
     }
 
-    public function withFacets(FacetFilter ...$facetFilters): PagedResultSet
+    public function withFacets(FacetTreeInterface ...$facetFilters): PagedResultSet
     {
         $c = clone $this;
         $c->facets = $facetFilters;
@@ -63,7 +63,7 @@ public function withFacets(FacetFilter ...$facetFilters): PagedResultSet
     }
 
     /**
-     * @return FacetFilter[]
+     * @return FacetTreeInterface[]
      */
     public function getFacets(): array
     {
diff --git a/tests/ElasticSearch/Aggregation/BucketTest.php b/tests/ElasticSearch/Aggregation/BucketTest.php
index 97c9acba..f3259500 100644
--- a/tests/ElasticSearch/Aggregation/BucketTest.php
+++ b/tests/ElasticSearch/Aggregation/BucketTest.php
@@ -4,7 +4,6 @@
 
 namespace CultuurNet\UDB3\Search\ElasticSearch\Aggregation;
 
-use InvalidArgumentException;
 use PHPUnit\Framework\TestCase;
 
 final class BucketTest extends TestCase
@@ -18,24 +17,4 @@ public function it_has_a_key_and_count(): void
         $this->assertEquals('key', $bucket->getKey());
         $this->assertEquals(10, $bucket->getCount());
     }
-
-    /**
-     * @test
-     */
-    public function it_checks_that_the_key_is_a_string(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $this->expectExceptionMessage('Bucket key should be a string.');
-        new Bucket(true, 10);
-    }
-
-    /**
-     * @test
-     */
-    public function it_checks_that_the_count_is_an_int(): void
-    {
-        $this->expectException(InvalidArgumentException::class);
-        $this->expectExceptionMessage('Bucket count should be an int.');
-        new Bucket('key', '10,000,0000');
-    }
 }