diff --git a/lib/runner.js b/lib/runner.js
index 2955be8..a83234a 100644
--- a/lib/runner.js
+++ b/lib/runner.js
@@ -12,14 +12,18 @@ function Runner(opts) {
 	EventEmitter.call(this);
 
 	this.results = [];
-	this.stats = {};
-	this.stats.failCount = 0;
-	this.stats.testCount = 0;
-	this.tests = {};
-	this.tests.concurrent = [];
-	this.tests.serial = [];
-	this.tests.before = [];
-	this.tests.after = [];
+
+	this.stats = {
+		failCount: 0,
+		testCount: 0
+	};
+
+	this.tests = {
+		concurrent: [],
+		serial: [],
+		before: [],
+		after: []
+	};
 }
 
 util.inherits(Runner, EventEmitter);
@@ -44,29 +48,33 @@ Runner.prototype.addAfterHook = function (title, cb) {
 };
 
 Runner.prototype.concurrent = function (tests) {
-	// run all tests
-	tests = tests.map(function (test) {
-		// in case of error, don't reject a promise
-		return test.run().catch(function () {
-			return;
-		}).then(function () {
-			this._addTestResult(test);
-		}.bind(this));
-	}, this);
+	var self = this;
 
-	return Promise.all(tests);
+	// run all tests
+	return Promise.all(tests.map(function (test) {
+		return test.run()
+			.catch(function () {
+				// in case of error, don't reject a promise
+				return;
+			})
+			.then(function () {
+				self._addTestResult(test);
+			});
+	}));
 };
 
 Runner.prototype.serial = function (tests) {
+	var self = this;
+
 	return Promise.resolve(tests).each(function (test) {
 		return test.run()
 			.catch(function () {
 				return;
 			})
 			.then(function () {
-				this._addTestResult(test);
-			}.bind(this));
-	}.bind(this));
+				self._addTestResult(test);
+			});
+	});
 };
 
 Runner.prototype._addTestResult = function (test) {
@@ -84,32 +92,29 @@ Runner.prototype._addTestResult = function (test) {
 };
 
 Runner.prototype.run = function () {
-	var concurrent = this.tests.concurrent;
-	var serial = this.tests.serial;
-	var before = this.tests.before;
-	var after = this.tests.after;
-
 	var self = this;
+	var tests = this.tests;
+	var stats = this.stats;
 
-	return this.serial(before)
+	return this.serial(tests.before)
 		.then(function () {
-			if (self.stats.failCount > 0) {
+			if (stats.failCount > 0) {
 				return Promise.reject();
 			}
 		})
 		.then(function () {
-			return self.serial(serial);
+			return self.serial(tests.serial);
 		})
 		.then(function () {
-			return self.concurrent(concurrent);
+			return self.concurrent(tests.concurrent);
 		})
 		.then(function () {
-			return self.serial(after);
+			return self.serial(tests.after);
 		})
 		.catch(function () {
 			return;
 		})
 		.then(function () {
-			self.stats.passCount = self.stats.testCount - self.stats.failCount;
+			stats.passCount = stats.testCount - stats.failCount;
 		});
 };