diff --git a/src/runtime/action/index.ts b/src/runtime/action/index.ts
index fe182b16d5..f712265c87 100644
--- a/src/runtime/action/index.ts
+++ b/src/runtime/action/index.ts
@@ -4,5 +4,5 @@ export interface ActionReturn<Parameters = any> {
 }
 
 export interface Action<Parameters = any> {
-	(node: HTMLElement, parameters: Parameters): void | ActionReturn<Parameters>;
+	(node: HTMLElement, parameters?: Parameters): void | ActionReturn<Parameters>;
 }