diff --git a/src/BaseRelation.php b/src/BaseRelation.php
index f4acd1e..031eecf 100644
--- a/src/BaseRelation.php
+++ b/src/BaseRelation.php
@@ -195,4 +195,16 @@ protected function matchForModel(Model $model, EloquentCollection $results)
 
         return $result;
     }
+
+    /**
+     * Get the plain foreign key.
+     *
+     * @return mixed
+     */
+    public function getForeignKeyName()
+    {
+        // Return a stub value for relation
+        // resolvers which need this function.
+        return NestedSet::PARENT_ID;
+    }
 }