diff --git a/src/models.ts b/src/models.ts
index 221016c..8df3a8d 100644
--- a/src/models.ts
+++ b/src/models.ts
@@ -1,5 +1,6 @@
-export interface Action {
+export interface Action<T = any> {
   readonly type: string;
+  readonly payload?: T;
 }
 
 export interface ActionReducer<T, V extends Action> {