diff --git a/index.js b/index.js
index a0748b2c..1fff734b 100644
--- a/index.js
+++ b/index.js
@@ -1,5 +1,6 @@
 'use strict';
 
+const CircuitBreaker = require('./lib/circuit');
 const Fidelity = require('fidelity');
 
 const defaults = {
@@ -12,99 +13,4 @@ const defaults = {
 function circuitBreaker (action, options) {
   return new CircuitBreaker(action, Object.assign({}, defaults, options));
 }
-
-const state = Symbol('state');
-const open = Symbol('open');
-const closed = Symbol('closed');
-const halfOpen = Symbol('half-open');
-const halfOpenAttempted = Symbol('half-open-attempted');
-const fallbackFunction = Symbol('fallback');
-
-class CircuitBreaker {
-  constructor (action, options) {
-    this.action = action;
-    this.options = options;
-    this.status = new Status();
-    this.Promise = options.Promise;
-    this[state] = closed;
-    this[fallbackFunction] = null;
-    this[halfOpenAttempted] = false;
-  }
-
-  get closed () {
-    return this[state] === closed;
-  }
-
-  get open () {
-    return this[state] === open;
-  }
-
-  get halfOpen () {
-    return this[state] === halfOpen;
-  }
-
-  fallback (func) {
-    this[fallbackFunction] = func;
-  }
-
-  fire () {
-    if (this.open || (this.halfOpen && this[halfOpenAttempted])) {
-      return failFast(this, Array.prototype.slice.call(arguments));
-    }
-
-    this[halfOpenAttempted] = this.halfOpen;
-    return new this.Promise((resolve, reject) => {
-      const timeout = setTimeout(() => {
-        fail(this);
-        reject(`Action timed out after ${this.options.timeout}ms`);
-      },
-      this.options.timeout);
-
-      this.action.apply(this.action, arguments)
-        .then((result) => {
-          succeed(this);
-          resolve(result);
-          clearTimeout(timeout);
-        })
-        .catch((err) => {
-          fail(this);
-          reject(err);
-          clearTimeout(timeout);
-        });
-    });
-  }
-}
-
-function failFast (circuit, args) {
-  if (circuit[fallbackFunction]) {
-    return new circuit.Promise((resolve, reject) => {
-      resolve(circuit[fallbackFunction].apply(circuit[fallbackFunction], args));
-    });
-  }
-  return circuit.Promise.reject('Breaker is open');
-}
-
-function succeed (circuit) {
-  circuit.status.failures = 0;
-  circuit.status.fires++;
-  circuit[state] = closed;
-}
-
-function fail (circuit) {
-  circuit.status.failures++;
-  if (circuit.status.failures >= circuit.options.maxFailures) {
-    circuit[state] = open;
-    setTimeout(() => {
-      circuit[state] = halfOpen;
-    }, circuit.options.resetTimeout).unref();
-  }
-}
-
-class Status {
-  constructor (failures, fires) {
-    this.failures = failures || 0;
-    this.fires = 0;
-  }
-}
-
 module.exports = exports = circuitBreaker;
diff --git a/lib/circuit.js b/lib/circuit.js
new file mode 100644
index 00000000..42f1e338
--- /dev/null
+++ b/lib/circuit.js
@@ -0,0 +1,97 @@
+'use strict';
+
+const state = Symbol('state');
+const open = Symbol('open');
+const closed = Symbol('closed');
+const halfOpen = Symbol('half-open');
+const halfOpenAttempted = Symbol('half-open-attempted');
+const fallbackFunction = Symbol('fallback');
+
+class CircuitBreaker {
+  constructor (action, options) {
+    this.action = action;
+    this.options = options;
+    this.status = new Status();
+    this.Promise = options.Promise;
+    this[state] = closed;
+    this[fallbackFunction] = null;
+    this[halfOpenAttempted] = false;
+  }
+
+  get closed () {
+    return this[state] === closed;
+  }
+
+  get open () {
+    return this[state] === open;
+  }
+
+  get halfOpen () {
+    return this[state] === halfOpen;
+  }
+
+  fallback (func) {
+    this[fallbackFunction] = func;
+  }
+
+  fire () {
+    if (this.open || (this.halfOpen && this[halfOpenAttempted])) {
+      return failFast(this, Array.prototype.slice.call(arguments));
+    }
+
+    this[halfOpenAttempted] = this.halfOpen;
+    return new this.Promise((resolve, reject) => {
+      const timeout = setTimeout(() => {
+        fail(this);
+        reject(`Action timed out after ${this.options.timeout}ms`);
+      },
+      this.options.timeout);
+
+      this.action.apply(this.action, arguments)
+        .then((result) => {
+          succeed(this);
+          resolve(result);
+          clearTimeout(timeout);
+        })
+        .catch((err) => {
+          fail(this);
+          reject(err);
+          clearTimeout(timeout);
+        });
+    });
+  }
+}
+
+function failFast (circuit, args) {
+  if (circuit[fallbackFunction]) {
+    return new circuit.Promise((resolve, reject) => {
+      resolve(circuit[fallbackFunction].apply(circuit[fallbackFunction], args));
+    });
+  }
+  return circuit.Promise.reject('Breaker is open');
+}
+
+function succeed (circuit) {
+  circuit.status.failures = 0;
+  circuit.status.fires++;
+  circuit[state] = closed;
+}
+
+function fail (circuit) {
+  circuit.status.failures++;
+  if (circuit.status.failures >= circuit.options.maxFailures) {
+    circuit[state] = open;
+    setTimeout(() => {
+      circuit[state] = halfOpen;
+    }, circuit.options.resetTimeout).unref();
+  }
+}
+
+class Status {
+  constructor (failures, fires) {
+    this.failures = failures || 0;
+    this.fires = 0;
+  }
+}
+
+module.exports = exports = CircuitBreaker;