diff --git a/db/card.php b/db/card.php
index e193e3a8a..874aadc1b 100644
--- a/db/card.php
+++ b/db/card.php
@@ -20,6 +20,7 @@ class Card extends Entity implements JsonSerializable {
         $this->addType('id','integer');
         $this->addType('stackId','integer');
         $this->addType('order','integer');
+        $this->addRelation('labels');
     }
 
     public function jsonSerialize() {
@@ -36,4 +37,4 @@ class Card extends Entity implements JsonSerializable {
             'labels' => $this->labels,
         ];
     }
-}
\ No newline at end of file
+}