diff --git a/src/Models/EboekhoudenRelation.php b/src/Models/EboekhoudenRelation.php
index dff6534..d86633f 100644
--- a/src/Models/EboekhoudenRelation.php
+++ b/src/Models/EboekhoudenRelation.php
@@ -3,10 +3,14 @@
 namespace IntVent\EBoekhouden\Models;
 
 use DateTime;
+use IntVent\EBoekhouden\Contracts\Arrayable;
 use IntVent\EBoekhouden\Exceptions\EboekhoudenException;
+use IntVent\EBoekhouden\Traits\ProtectedFieldsToArrayTrait;
 
-class EboekhoudenRelation
+class EboekhoudenRelation implements Arrayable
 {
+    use ProtectedFieldsToArrayTrait;
+
     protected ?int $id = null;
     protected string $relation_type = 'B';
     protected string $la = '0';
diff --git a/src/Traits/ProtectedFieldsToArrayTrait.php b/src/Traits/ProtectedFieldsToArrayTrait.php
index 7ccaeae..75f1aac 100644
--- a/src/Traits/ProtectedFieldsToArrayTrait.php
+++ b/src/Traits/ProtectedFieldsToArrayTrait.php
@@ -10,7 +10,7 @@ public function toArray()
         foreach ($return as $key => $value) {
             if (is_array($value)) {
                 $return[$key] = array_map(
-                    fn ($item): array => $item->toArray(),
+                    fn ($item) => method_exists($item, 'toArray') ? $item->toArray() : $item,
                     $value
                 );
             }