diff --git a/src/Updux.test.js b/src/Updux.test.ts
similarity index 100%
rename from src/Updux.test.js
rename to src/Updux.test.ts
diff --git a/src/Updux.ts b/src/Updux.ts
index fbed23d..170a7af 100644
--- a/src/Updux.ts
+++ b/src/Updux.ts
@@ -11,7 +11,14 @@ import { action } from './actions';
 import { buildUpreducer } from './buildUpreducer';
 import { buildMiddleware, augmentMiddlewareApi } from './buildMiddleware';
 
-import { AggregateDuxActions, AggregateDuxState, Dict } from './types';
+import {
+    AggregateDuxActions,
+    AggregateDuxState,
+    Dict,
+    ItemsOf,
+    Reducer,
+    Upreducer,
+} from './types';
 
 /**
  * Configuration object typically passed to the constructor of the class Updux.
@@ -70,6 +77,28 @@ export interface UpduxConfig<
      * reaction for the mapped dux.
      */
     mappedReaction?: Function | boolean;
+
+    /**
+     * Wrapping function for the upreducer to provides full customization.
+     * @example
+     * // if an action has the 'dontDoIt' meta flag, don't do anything
+     * const dux = new Updux({
+     *    ...,
+     *    upreducerWrapper: (upreducer) => action => {
+     *        if( action?.meta?.dontDoIt ) return state => state;
+     *        return upreducer(action);
+     *    }
+     * })
+     */
+    upreducerWrapper?: (
+        upreducer: Upreducer<
+            AggregateDuxState<TState, TSubduxes>,
+            ItemsOf<AggregateDuxActions<TActions, TSubduxes>>
+        >
+    ) => Upreducer<
+        AggregateDuxState<TState, TSubduxes>,
+        ItemsOf<AggregateDuxActions<TActions, TSubduxes>>
+    >;
 }
 
 export class Updux<
@@ -90,6 +119,7 @@ export class Updux<
     #reactions = [];
     #mappedSelectors = undefined;
     #mappedReaction = undefined;
+    #upreducerWrapper = undefined;
 
     constructor(config: UpduxConfig<TState, TActions, TSelectors, TSubduxes>) {
         this.#initial = config.initial ?? {};
@@ -130,6 +160,8 @@ export class Updux<
         this.#reactions = config.reactions ?? [];
 
         this.#mappedReaction = config.mappedReaction;
+
+        this.#upreducerWrapper = config.upreducerWrapper;
     }
 
     #memoInitial = moize(buildInitial);
@@ -171,15 +203,22 @@ export class Updux<
         );
     }
 
-    get upreducer() {
+    get upreducer(): Upreducer<
+        AggregateDuxState<TState, TSubduxes>,
+        ItemsOf<AggregateDuxActions<TActions, TSubduxes>>
+    > {
         return this.#memoUpreducer(
             this.initial,
             this.#mutations,
-            this.#subduxes
+            this.#subduxes,
+            this.#upreducerWrapper
         );
     }
 
-    get reducer() {
+    get reducer(): Reducer<
+        AggregateDuxState<TState, TSubduxes>,
+        ItemsOf<AggregateDuxActions<TActions, TSubduxes>>
+    > {
         return (state, action) => this.upreducer(action)(state);
     }
 
@@ -340,7 +379,7 @@ export class Updux<
             selectors: Record<string, Function>;
             actions: AggregateDuxActions<TActions, TSubduxes>;
         } = reduxCreateStore(
-            this.reducer,
+            this.reducer as any,
             initial ?? this.initial,
             enhancer
         ) as any;
diff --git a/src/actions.ts b/src/actions.ts
index 03d1328..9db8252 100644
--- a/src/actions.ts
+++ b/src/actions.ts
@@ -1,4 +1,4 @@
-export type Action<T extends string = string, TPayload = unknown> = {
+export type Action<T extends string = string, TPayload = any> = {
     type: T;
     meta?: Record<string, unknown>;
 } & {
diff --git a/src/buildUpreducer.js b/src/buildUpreducer.js
index e544a74..97f4f81 100644
--- a/src/buildUpreducer.js
+++ b/src/buildUpreducer.js
@@ -1,13 +1,18 @@
 import u from 'updeep';
 import { mapValues } from 'lodash';
 
-export function buildUpreducer(initial, mutations, subduxes = {}) {
+export function buildUpreducer(
+    initial,
+    mutations,
+    subduxes = {},
+    wrapper = undefined
+) {
     const subReducers =
         Object.keys(subduxes).length > 0
             ? mapValues(subduxes, ({ upreducer }) => upreducer)
             : null;
 
-    return (action) => (state) => {
+    const upreducer = (action) => (state) => {
         if (!action?.type)
             throw new Error('upreducer called with a bad action');
 
@@ -35,4 +40,6 @@ export function buildUpreducer(initial, mutations, subduxes = {}) {
 
         return a(action.payload, action)(newState);
     };
+
+    return wrapper ? wrapper(upreducer) : upreducer;
 }
diff --git a/src/types.ts b/src/types.ts
index d969524..def3484 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,5 +1,16 @@
+import { Action } from './actions';
+
 export type Dict<T> = Record<string, T>;
 
+export type Upreducer<TState = any, TAction = Action> = (
+    action: Action
+) => (state: TState) => TState;
+
+export type Reducer<TState = any, TAction = Action> = (
+    state: TState | undefined,
+    action: Action
+) => TState;
+
 export type UnionToIntersection<U> = (
     U extends any ? (k: U) => void : never
 ) extends (k: infer I) => void
@@ -31,7 +42,7 @@ export type AggregateDuxState<TState, TSubduxes> = TState &
 
 type DuxActionsSubduxes<C> = C extends object ? ActionsOf<C[keyof C]> : unknown;
 
-type ItemsOf<C> = C extends object ? C[keyof C] : unknown;
+export type ItemsOf<C> = C extends object ? C[keyof C] : unknown;
 
 export type AggregateDuxActions<TActions, TSubduxes> = TActions &
     UnionToIntersection<ActionsOf<ItemsOf<TSubduxes>>>;