diff --git a/jest.config.js b/jest.config.js
index 2d94fac..096fb97 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,6 +1,6 @@
 module.exports = {
   "roots": [
-    "./src"
+    "./dist"
   ],
   "transform": {
     "^.+\\.ts$": "ts-jest",
diff --git a/src/middleware.test.ts b/src/middleware.test.ts
index 54d02a9..e3a0a1c 100644
--- a/src/middleware.test.ts
+++ b/src/middleware.test.ts
@@ -1,228 +1,277 @@
-import Updux, { actionCreator } from ".";
-import u from "updeep";
+import Updux, { actionCreator } from '.';
+import u from 'updeep';
+import mwUpdux from './middleware_aux';
 
-test("simple effect", () => {
-  const tracer = jest.fn();
+test('simple effect', () => {
+    const tracer = jest.fn();
 
-  const store = new Updux({
-    effects: {
-      foo: (api: any) => (next: any) => (action: any) => {
-        tracer();
-        next(action);
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch({ type: "bar" });
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch.foo();
-
-  expect(tracer).toHaveBeenCalled();
-});
-
-test("effect and sub-effect", () => {
-  const tracer = jest.fn();
-
-  const tracerEffect = (signature: string) => (api: any) => (next: any) => (
-    action: any
-  ) => {
-    tracer(signature);
-    next(action);
-  };
-
-  const store = new Updux({
-    effects: {
-      foo: tracerEffect("root")
-    },
-    subduxes: {
-      zzz: {
+    const store = new Updux({
         effects: {
-          foo: tracerEffect("child")
-        }
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch({ type: "bar" });
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch.foo();
-
-  expect(tracer).toHaveBeenNthCalledWith(1, "root");
-  expect(tracer).toHaveBeenNthCalledWith(2, "child");
-});
-
-test('"*" effect', () => {
-  const tracer = jest.fn();
-
-  const store = new Updux({
-    effects: {
-      "*": api => next => action => {
-        tracer();
-        next(action);
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch({ type: "bar" });
-
-  expect(tracer).toHaveBeenCalled();
-});
-
-test("async effect", async () => {
-  function timeout(ms: number) {
-    return new Promise(resolve => setTimeout(resolve, ms));
-  }
-
-  const tracer = jest.fn();
-
-  const store = new Updux({
-    effects: {
-      foo: api => next => async action => {
-        next(action);
-        await timeout(1000);
-        tracer();
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch.foo();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  await timeout(1000);
-
-  expect(tracer).toHaveBeenCalled();
-});
-
-test("getState is local", () => {
-  let childState;
-  let rootState;
-  let rootFromChild;
-
-  const child = new Updux({
-    initial: { alpha: 12 },
-    effects: {
-      doIt: ({ getState, getRootState }) => next => action => {
-        childState = getState();
-        rootFromChild = getRootState();
-        next(action);
-      }
-    }
-  });
-
-  const root = new Updux({
-    initial: { beta: 24 },
-    subduxes: { child },
-    effects: {
-      doIt: ({ getState }) => next => action => {
-        rootState = getState();
-        next(action);
-      }
-    }
-  });
-
-  const store = root.createStore();
-  store.dispatch.doIt();
-
-  expect(rootState).toEqual({ beta: 24, child: { alpha: 12 } });
-  expect(rootFromChild).toEqual({ beta: 24, child: { alpha: 12 } });
-  expect(childState).toEqual({ alpha: 12 });
-});
-
-test("middleware as map", () => {
-  let childState;
-  let rootState;
-  let rootFromChild;
-
-  const doIt = actionCreator("doIt");
-
-  const child = new Updux({
-    initial: "",
-    effects: [
-      [
-        doIt,
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "Child" }, action) as any);
-        }
-      ]
-    ]
-  });
-
-  const root = new Updux({
-    initial: { message: "" },
-    subduxes: { child },
-    effects: [
-      [
-        "^",
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "Pre" }, action) as any);
-        }
-      ],
-      [
-        doIt,
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "Root" }, action) as any);
-        }
-      ],
-      [
-        "*",
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "After" }, action) as any);
-        }
-      ],
-      [
-        "$",
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "End" }, action) as any);
-        }
-      ]
-    ],
-    mutations: [[doIt, (message: any) => () => ({ message })]]
-  });
-
-  const store = root.createStore();
-  store.dispatch.doIt("");
-
-  expect(store.getState()).toEqual({ message: "PreRootAfterChildEnd" });
-});
-
-test("generator", () => {
-  const updux = new Updux({
-    initial: 0,
-    mutations: [["doIt", payload => () => payload]],
-    effects: [
-      [
-        "doIt",
-        () => {
-          let i = 0;
-          return () => (next: any) => (action: any) =>
-            next({ ...action, payload: ++i });
+            foo: (api: any) => (next: any) => (action: any) => {
+                tracer();
+                next(action);
+            },
         },
-        true
-      ]
-    ]
-  });
+    }).createStore();
 
-  const store1 = updux.createStore();
-  store1.dispatch.doIt();
-  expect(store1.getState()).toEqual(1);
-  store1.dispatch.doIt();
-  expect(store1.getState()).toEqual(2);
-  updux.actions;
+    expect(tracer).not.toHaveBeenCalled();
 
-  const store2 = updux.createStore();
-  store2.dispatch.doIt();
-  expect(store2.getState()).toEqual(1);
+    store.dispatch({ type: 'bar' });
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch.foo();
+
+    expect(tracer).toHaveBeenCalled();
+});
+
+test('effect and sub-effect', () => {
+    const tracer = jest.fn();
+
+    const tracerEffect = (signature: string) => (api: any) => (next: any) => (
+        action: any
+    ) => {
+        tracer(signature);
+        next(action);
+    };
+
+    const store = new Updux({
+        effects: {
+            foo: tracerEffect('root'),
+        },
+        subduxes: {
+            zzz: {
+                effects: {
+                    foo: tracerEffect('child'),
+                },
+            },
+        },
+    }).createStore();
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch({ type: 'bar' });
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch.foo();
+
+    expect(tracer).toHaveBeenNthCalledWith(1, 'root');
+    expect(tracer).toHaveBeenNthCalledWith(2, 'child');
+});
+
+describe('"*" effect', () => {
+    test('from the constructor', () => {
+        const tracer = jest.fn();
+
+        const store = new Updux({
+            effects: {
+                '*': api => next => action => {
+                    tracer();
+                    next(action);
+                },
+            },
+        }).createStore();
+
+        expect(tracer).not.toHaveBeenCalled();
+
+        store.dispatch({ type: 'bar' });
+
+        expect(tracer).toHaveBeenCalled();
+    });
+
+    test('from addEffect', () => {
+        const tracer = jest.fn();
+
+        const updux = new Updux({});
+
+        updux.addEffect('*', api => next => action => {
+            tracer();
+            next(action);
+        });
+
+        expect(tracer).not.toHaveBeenCalled();
+
+        updux.createStore().dispatch({ type: 'bar' });
+
+        expect(tracer).toHaveBeenCalled();
+    });
+
+    test('action can be modified', () => {
+
+        const mw = mwUpdux.middleware;
+
+        const next = jest.fn();
+
+        mw({dispatch:{}} as any)(next as any)({type: 'bar'});
+
+        expect(next).toHaveBeenCalled();
+
+        expect(next.mock.calls[0][0]).toMatchObject({meta: 'gotcha'});
+    });
+});
+
+test('async effect', async () => {
+    function timeout(ms: number) {
+        return new Promise(resolve => setTimeout(resolve, ms));
+    }
+
+    const tracer = jest.fn();
+
+    const store = new Updux({
+        effects: {
+            foo: api => next => async action => {
+                next(action);
+                await timeout(1000);
+                tracer();
+            },
+        },
+    }).createStore();
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch.foo();
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    await timeout(1000);
+
+    expect(tracer).toHaveBeenCalled();
+});
+
+test('getState is local', () => {
+    let childState;
+    let rootState;
+    let rootFromChild;
+
+    const child = new Updux({
+        initial: { alpha: 12 },
+        effects: {
+            doIt: ({ getState, getRootState }) => next => action => {
+                childState = getState();
+                rootFromChild = getRootState();
+                next(action);
+            },
+        },
+    });
+
+    const root = new Updux({
+        initial: { beta: 24 },
+        subduxes: { child },
+        effects: {
+            doIt: ({ getState }) => next => action => {
+                rootState = getState();
+                next(action);
+            },
+        },
+    });
+
+    const store = root.createStore();
+    store.dispatch.doIt();
+
+    expect(rootState).toEqual({ beta: 24, child: { alpha: 12 } });
+    expect(rootFromChild).toEqual({ beta: 24, child: { alpha: 12 } });
+    expect(childState).toEqual({ alpha: 12 });
+});
+
+test('middleware as map', () => {
+    let childState;
+    let rootState;
+    let rootFromChild;
+
+    const doIt = actionCreator('doIt');
+
+    const child = new Updux({
+        initial: '',
+        effects: [
+            [
+                doIt,
+                () => next => action => {
+                    next(
+                        u(
+                            { payload: (p: string) => p + 'Child' },
+                            action
+                        ) as any
+                    );
+                },
+            ],
+        ],
+    });
+
+    const root = new Updux({
+        initial: { message: '' },
+        subduxes: { child },
+        effects: [
+            [
+                '^',
+                () => next => action => {
+                    next(
+                        u({ payload: (p: string) => p + 'Pre' }, action) as any
+                    );
+                },
+            ],
+            [
+                doIt,
+                () => next => action => {
+                    next(
+                        u({ payload: (p: string) => p + 'Root' }, action) as any
+                    );
+                },
+            ],
+            [
+                '*',
+                () => next => action => {
+                    next(
+                        u(
+                            { payload: (p: string) => p + 'After' },
+                            action
+                        ) as any
+                    );
+                },
+            ],
+            [
+                '$',
+                () => next => action => {
+                    next(
+                        u({ payload: (p: string) => p + 'End' }, action) as any
+                    );
+                },
+            ],
+        ],
+        mutations: [[doIt, (message: any) => () => ({ message })]],
+    });
+
+    const store = root.createStore();
+    store.dispatch.doIt('');
+
+    expect(store.getState()).toEqual({ message: 'PreRootAfterChildEnd' });
+});
+
+test('generator', () => {
+    const updux = new Updux({
+        initial: 0,
+        mutations: [['doIt', payload => () => payload]],
+        effects: [
+            [
+                'doIt',
+                () => {
+                    let i = 0;
+                    return () => (next: any) => (action: any) =>
+                        next({ ...action, payload: ++i });
+                },
+                true,
+            ],
+        ],
+    });
+
+    const store1 = updux.createStore();
+    store1.dispatch.doIt();
+    expect(store1.getState()).toEqual(1);
+    store1.dispatch.doIt();
+    expect(store1.getState()).toEqual(2);
+    updux.actions;
+
+    const store2 = updux.createStore();
+    store2.dispatch.doIt();
+    expect(store2.getState()).toEqual(1);
 });
diff --git a/src/middleware_aux.ts b/src/middleware_aux.ts
new file mode 100644
index 0000000..47ab313
--- /dev/null
+++ b/src/middleware_aux.ts
@@ -0,0 +1,13 @@
+import Updux from '.';
+
+const updux = new Updux({
+    subduxes: {
+        foo: { initial: "banana" }
+    }
+});
+
+updux.addEffect('*', api => next => action => {
+    next({...action, meta: "gotcha" });
+});
+
+export default updux;