diff --git a/src/Discord/Helpers/CollectionInterface.php b/src/Discord/Helpers/CollectionInterface.php
index 1f4cef9f1..8b138a4d5 100644
--- a/src/Discord/Helpers/CollectionInterface.php
+++ b/src/Discord/Helpers/CollectionInterface.php
@@ -43,7 +43,7 @@ public function offsetExists($offset): bool;
     public function offsetGet($offset);
     public function offsetSet($offset, $value): void;
     public function offsetUnset($offset): void;
-    public function serialize(): string;
+    public function serialize(int $flags, int $depth): string;
     public function __serialize(): array;
     public function unserialize(string $serialized): void;
     public function __unserialize(array $data): void;
diff --git a/src/Discord/Helpers/CollectionTrait.php b/src/Discord/Helpers/CollectionTrait.php
index 7a189b90c..97466d322 100644
--- a/src/Discord/Helpers/CollectionTrait.php
+++ b/src/Discord/Helpers/CollectionTrait.php
@@ -433,7 +433,7 @@ public function offsetUnset($offset): void
      *
      * @return string
      */
-    public function serialize(): string
+    public function serialize(int $flags, int $depth): string
     {
         return json_encode($this->items);
     }