diff --git a/src/Jenssegers/Mongodb/Relations/BelongsToMany.php b/src/Jenssegers/Mongodb/Relations/BelongsToMany.php
index 98d842139..4db430f88 100644
--- a/src/Jenssegers/Mongodb/Relations/BelongsToMany.php
+++ b/src/Jenssegers/Mongodb/Relations/BelongsToMany.php
@@ -47,7 +47,7 @@ public function addConstraints()
 	 * @param  bool   $detaching
 	 * @return void
 	 */
-	public function sync(array $ids, $detaching = true)
+	public function sync($ids, $detaching = true)
 	{
 		if ($ids instanceof Collection) $ids = $ids->modelKeys();