diff --git a/package.json b/package.json
index 45262dc..a6bd8bf 100644
--- a/package.json
+++ b/package.json
@@ -66,7 +66,7 @@
         "url": "https://github.com/yanick/updux/issues"
     },
     "homepage": "https://github.com/yanick/updux#readme",
-    "types": "./types/index.d.ts",
+    "types": "./dist/index.d.ts",
     "prettier": {
         "tabWidth": 4,
         "singleQuote": true,
diff --git a/src/Updux.ts b/src/Updux.ts
index 76e32e2..fbb65d3 100644
--- a/src/Updux.ts
+++ b/src/Updux.ts
@@ -152,10 +152,7 @@ export class Updux {
         return this.#memoInitial(this.#initial, this.#subduxes);
     }
 
-    /**
-     *   @return {Record<string,Function>}
-     */
-    get actions() {
+    get actions(): Record<string, Function> {
         return this.#memoActions(this.#actions, this.#subduxes);
     }
 
@@ -183,7 +180,7 @@ export class Updux {
         this.#reactions = [...this.#reactions, subscription];
     }
 
-    setAction(type, payloadFunc) {
+    setAction(type, payloadFunc?: Function) {
         const theAction = action(type, payloadFunc);
 
         this.#actions = { ...this.#actions, [type]: theAction };
@@ -325,10 +322,10 @@ export class Updux {
         };
     }
 
-    createStore(initial) {
+    createStore(initial?: unknown) {
         const store : {
-            getState: Function,
-            dispatch: Function,
+            getState: Function & Record<string,Function>,
+            dispatch: Function & Record<string,Function>,
             selectors: Record<string,Function>,
             actions: Record<string,Function>,
         } = reduxCreateStore(
diff --git a/src/actions.js b/src/actions.js
deleted file mode 100644
index ab7b7c7..0000000
--- a/src/actions.js
+++ /dev/null
@@ -1,17 +0,0 @@
-export function action(type, payloadFunction = null) {
-    const generator = function (payloadArg) {
-        const result = { type };
-
-        if (payloadFunction) {
-            result.payload = payloadFunction(payloadArg);
-        } else {
-            if (payloadArg !== undefined) result.payload = payloadArg;
-        }
-
-        return result;
-    };
-
-    generator.type = type;
-
-    return generator;
-}
diff --git a/src/actions.ts b/src/actions.ts
new file mode 100644
index 0000000..c265700
--- /dev/null
+++ b/src/actions.ts
@@ -0,0 +1,39 @@
+export type Action<T extends string=string,TPayload=unknown> = {
+    type: T; meta?: Record<string,unknown>; } & (
+    {       payload?: TPayload }
+)
+
+export type ActionGenerator<TType extends string = string, TPayloadGen = undefined> = {
+    type: TType;
+} & (TPayloadGen extends (...args:any) => any
+    ? (...args: Parameters<TPayloadGen>) => {
+          type: TType;
+          payload: ReturnType<TPayloadGen>;
+      }
+    : (...args: any[]) => { type: TType; payload?: unknown });
+
+// interface Action {
+//     <T extends string = string>(actionType: T): ActionGenerator<T>;
+//     <T extends string = string, F extends Function = Function>(
+//         actionType: T,
+//         payloadGen: F
+//     ): ActionGenerator<T, F>;
+// }
+
+export function action(type, payloadFunction = null) {
+    const generator = function (...payloadArg) {
+        const result :Action = { type };
+
+        if (payloadFunction) {
+            result.payload = payloadFunction(...payloadArg);
+        } else {
+            if (payloadArg[0] !== undefined) result.payload = payloadArg[0];
+        }
+
+        return result;
+    };
+
+    generator.type = type;
+
+    return generator;
+}
diff --git a/src/buildSelectors/index.ts b/src/buildSelectors/index.ts
index 2949a23..82c0904 100644
--- a/src/buildSelectors/index.ts
+++ b/src/buildSelectors/index.ts
@@ -5,7 +5,7 @@ export function buildSelectors(localSelectors, splatSelector = {}, subduxes ={})
         if (!selectors) return {};
         if (slice === '*') return {};
 
-        return mapValues(selectors, (func) => (state) => func(state[slice]));
+        return mapValues(selectors, (func: Function) => (state) => func(state[slice]));
     });
 
     let splat = {};
diff --git a/src/buildUpreducer.js b/src/buildUpreducer.js
index ba53fba..6d6bb54 100644
--- a/src/buildUpreducer.js
+++ b/src/buildUpreducer.js
@@ -8,6 +8,8 @@ export function buildUpreducer(initial, mutations, subduxes = {}) {
             : null;
 
     return (action) => (state) => {
+        if( !action?.type ) throw new Error("upreducer called with a bad action");
+
         let newState = state ?? initial;
 
         if (subReducers) {