diff --git a/package.json b/package.json
index f5f1670..f1ab40b 100644
--- a/package.json
+++ b/package.json
@@ -6,11 +6,13 @@
   "license": "MIT",
   "main": "lib/index.js",
   "scripts": {
+    "test": "babel-tape-runner test/*.js",
     "prepublish": "rm -rf lib && babel src --out-dir lib",
     "postpublish": "rm -rf lib"
   },
   "dependencies": {},
   "devDependencies": {
+    "babel-cli": "^6.6.5",
     "babel-preset-es2015": "^6.3.13",
     "babel-tape-runner": "^2.0.0",
     "tape": "^4.2.0"
diff --git a/src/index.js b/src/index.js
index 071c785..f6138d9 100644
--- a/src/index.js
+++ b/src/index.js
@@ -8,29 +8,18 @@ const RANDOM = 'EFFECT_RANDOM'
  * Random number generator
  */
 
-function random (rng=Math.random.bind(Math)) {
-  return () => next => effect =>
-    effect.type === RANDOM
+function randomMiddleware (rng = () => Math.random()) {
+  return () => next => action =>
+    action.type === RANDOM
       ? Promise.resolve(rng())
-      : next(effect)
+      : next(action)
 }
 
-/**
- * Action creator
- */
-
- function random () {
-   return {
-     type: RANDOM
-   }
- }
-
-
 /**
  * Exports
  */
 
-export default random
+export default randomMiddleware
 export {
-  random
+  RANDOM
 }
diff --git a/test/index.js b/test/index.js
index 37c44fc..b764aee 100644
--- a/test/index.js
+++ b/test/index.js
@@ -3,20 +3,40 @@
  */
 
 import test from 'tape'
-import random from '../src'
+import random, { RANDOM } from '../src'
 
 /**
  * Tests
  */
 
-test('should work', ({equal, end}) => {
-  const mw = random(rfc1149)({})(() => {})
+test(`should resolve number when using custom random function`, ({equal, end}) => {
+  const next = (action) => action
+  const mw = random(() => 4)()(next)
+
+  mw({ type: RANDOM }).then((value) => {
+    equal(value, 4)
+  })
+
+  end()
+})
+
+test(`should resolve number when using default random function`, ({equal, end}) => {
+  const next = (action) => action
+  const mw = random()()(next)
+
+  mw({ type: RANDOM }).then((value) => {
+    equal(typeof value, 'number')
+  })
 
-  equal(mw({type: 'RANDOM'}), 4)
   end()
 })
 
-function rfc1149 () {
-  // Chosen by fair dice roll
-  return 4
-}
+
+test('should return next action when action type is ANY', ({equal, end}) => {
+  const next = (action) => action
+  const mw = random()()(next)
+
+  equal(mw({ type: 'ANY' }).type, 'ANY')
+
+  end()
+})