diff --git a/.eslintrc b/.eslintrc
index 7074004..bd1a5e0 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -5,36 +5,25 @@
 
 	"rules": {
 		"array-element-newline": 0,
-		"camelcase": 1,
-		"comma-dangle": 1,
 		"complexity": 0,
-		"curly": 1,
-		"dot-notation": 1,
-		"func-style": 1,
+		"func-style": [2, "declaration"],
 		"max-lines-per-function": 0,
 		"max-nested-callbacks": 1,
+		"max-statements-per-line": 1,
 		"max-statements": 0,
 		"multiline-comment-style": 0,
-		"no-array-constructor": 1,
 		"no-continue": 1,
-		"no-div-regex": 1,
-		"no-extra-parens": 1,
-		"no-mixed-operators": 1,
 		"no-param-reassign": 1,
-		"no-plusplus": 1,
-		"no-proto": 1,
-		"no-redeclare": 1,
 		"no-restricted-syntax": 1,
-		"no-shadow": 1,
-		"no-unused-vars": 1,
-		"no-use-before-define": 1,
-		"object-curly-newline": 1,
-		"operator-linebreak": 1,
-		"quote-props": 1,
-		"quotes": 1,
-		"semi-style": 1,
-		"semi": 1,
-		"strict": 1,
-		"wrap-regex": 1,
+		"object-curly-newline": 0,
 	},
+
+	"overrides": [
+		{
+			"files": "test/**",
+			"rules": {
+				"camelcase": 0,
+			},
+		},
+	]
 }
diff --git a/example/parse.js b/example/parse.js
index abff3e8..9e982e1 100644
--- a/example/parse.js
+++ b/example/parse.js
@@ -1,2 +1,4 @@
+'use strict';
+
 var argv = require('../')(process.argv.slice(2));
 console.dir(argv);
diff --git a/index.js b/index.js
index 5ce6216..ad21027 100644
--- a/index.js
+++ b/index.js
@@ -1,12 +1,57 @@
+'use strict';
+
+function isNumber(x) {
+	if (typeof x === 'number') { return true; }
+	if ((/^0x[0-9a-f]+$/i).test(x)) { return true; }
+	return (/^[-+]?(?:\d+(?:\.\d*)?|\.\d+)(e[-+]?\d+)?$/).test(x);
+}
+
+function setKey(obj, keys, value) {
+	var o = obj;
+	var key;
+	for (var i = 0; i < keys.length - 1; i++) {
+		key = keys[i];
+		if (key === '__proto__') { return; }
+		if (o[key] === undefined) { o[key] = {}; }
+		if (o[key] === Object.prototype || o[key] === Number.prototype
+            || o[key] === String.prototype) { o[key] = {}; }
+		if (o[key] === Array.prototype) { o[key] = []; }
+		o = o[key];
+	}
+
+	key = keys[keys.length - 1];
+	if (key === '__proto__') { return; }
+	if (o === Object.prototype || o === Number.prototype
+        || o === String.prototype) { o = {}; }
+	if (o === Array.prototype) { o = []; }
+	if (o[key] === undefined || typeof o[key] === 'boolean') {
+		o[key] = value;
+	} else if (Array.isArray(o[key])) {
+		o[key].push(value);
+	} else {
+		o[key] = [o[key], value];
+	}
+}
+
+function hasKey(obj, keys) {
+	var o = obj;
+	keys.slice(0, -1).forEach(function (key) {
+		o = o[key] || {};
+	});
+
+	var key = keys[keys.length - 1];
+	return key in o;
+}
+
 module.exports = function (args, opts) {
-	if (!opts) opts = {};
+	if (!opts) { opts = {}; }
 
 	var flags = { bools: {}, strings: {} };
 
-	if (typeof opts['boolean'] === 'boolean' && opts['boolean']) {
+	if (typeof opts.boolean === 'boolean' && opts.boolean) {
 		flags.allBools = true;
 	} else {
-		[].concat(opts['boolean']).filter(Boolean).forEach(function (key) {
+		[].concat(opts.boolean).filter(Boolean).forEach(function (key) {
 			flags.bools[key] = true;
 		});
 	}
@@ -28,9 +73,20 @@ module.exports = function (args, opts) {
 		}
 	});
 
-	var defaults = opts['default'] || {};
+	var defaults = opts.default || {};
 
 	var argv = { _: [] };
+
+	function setArg(key, val) {
+		var value = !flags.strings[key] && isNumber(val)
+			? Number(val) : val;
+		setKey(argv, key.split('.'), value);
+
+		(aliases[key] || []).forEach(function (x) {
+			setKey(argv, x.split('.'), value);
+		});
+	}
+
 	Object.keys(flags.bools).forEach(function (key) {
 		setArg(key, defaults[key] === undefined ? false : defaults[key]);
 	});
@@ -42,58 +98,49 @@ module.exports = function (args, opts) {
 		args = args.slice(0, args.indexOf('--'));
 	}
 
-	function setArg(key, val) {
-		var value = !flags.strings[key] && isNumber(val)
-			? Number(val) : val
-        ;
-		setKey(argv, key.split('.'), value);
-
-		(aliases[key] || []).forEach(function (x) {
-			setKey(argv, x.split('.'), value);
-		});
-	}
-
 	for (var i = 0; i < args.length; i++) {
 		var arg = args[i];
+		var key;
+		var next;
 
-		if (/^--.+=/.test(arg)) {
+		if ((/^--.+=/).test(arg)) {
 			// Using [\s\S] instead of . because js doesn't support the
 			// 'dotall' regex modifier. See:
 			// http://stackoverflow.com/a/1068308/13216
 			var m = arg.match(/^--([^=]+)=([\s\S]*)$/);
 			setArg(m[1], m[2]);
-		} else if (/^--no-.+/.test(arg)) {
-			var key = arg.match(/^--no-(.+)/)[1];
+		} else if ((/^--no-.+/).test(arg)) {
+			key = arg.match(/^--no-(.+)/)[1];
 			setArg(key, false);
-		} else if (/^--.+/.test(arg)) {
-			var key = arg.match(/^--(.+)/)[1];
-			var next = args[i + 1];
-			if (next !== undefined && !/^-/.test(next)
+		} else if ((/^--.+/).test(arg)) {
+			key = arg.match(/^--(.+)/)[1];
+			next = args[i + 1];
+			if (next !== undefined && !(/^-/).test(next)
             && !flags.bools[key]
             && !flags.allBools
             && (aliases[key] ? !flags.bools[aliases[key]] : true)) {
 				setArg(key, next);
-				i++;
-			} else if (/^(true|false)$/.test(next)) {
+				i += 1;
+			} else if ((/^(true|false)$/).test(next)) {
 				setArg(key, next === 'true');
-				i++;
+				i += 1;
 			} else {
 				setArg(key, flags.strings[key] ? '' : true);
 			}
-		} else if (/^-[^-]+/.test(arg)) {
+		} else if ((/^-[^-]+/).test(arg)) {
 			var letters = arg.slice(1, -1).split('');
 
 			var broken = false;
 			for (var j = 0; j < letters.length; j++) {
-				var next = arg.slice(j + 2);
+				next = arg.slice(j + 2);
 
 				if (next === '-') {
-					setArg(letters[j], next)
+					setArg(letters[j], next);
 					continue;
 				}
 
-				if (/[A-Za-z]/.test(letters[j])
-                && /-?\d+(\.\d*)?(e-?\d+)?$/.test(next)) {
+				if ((/[A-Za-z]/).test(letters[j])
+                && (/-?\d+(\.\d*)?(e-?\d+)?$/).test(next)) {
 					setArg(letters[j], next);
 					broken = true;
 					break;
@@ -108,88 +155,43 @@ module.exports = function (args, opts) {
 				}
 			}
 
-			var key = arg.slice(-1)[0];
+			key = arg.slice(-1)[0];
 			if (!broken && key !== '-') {
-				if (args[i + 1] && !/^(-|--)[^-]/.test(args[i + 1])
+				if (args[i + 1] && !(/^(-|--)[^-]/).test(args[i + 1])
                 && !flags.bools[key]
                 && (aliases[key] ? !flags.bools[aliases[key]] : true)) {
 					setArg(key, args[i + 1]);
-					i++;
-				} else if (args[i + 1] && /true|false/.test(args[i + 1])) {
+					i += 1;
+				} else if (args[i + 1] && (/true|false/).test(args[i + 1])) {
 					setArg(key, args[i + 1] === 'true');
-					i++;
+					i += 1;
 				} else {
 					setArg(key, flags.strings[key] ? '' : true);
 				}
 			}
 		} else {
-			argv._.push(flags.strings['_'] || !isNumber(arg) ? arg : Number(arg));
+			argv._.push(flags.strings._ || !isNumber(arg) ? arg : Number(arg));
 		}
 	}
 
-	Object.keys(defaults).forEach(function (key) {
-		if (!hasKey(argv, key.split('.'))) {
-			setKey(argv, key.split('.'), defaults[key]);
+	Object.keys(defaults).forEach(function (k) {
+		if (!hasKey(argv, k.split('.'))) {
+			setKey(argv, k.split('.'), defaults[k]);
 
-			(aliases[key] || []).forEach(function (x) {
-				setKey(argv, x.split('.'), defaults[key]);
+			(aliases[k] || []).forEach(function (x) {
+				setKey(argv, x.split('.'), defaults[k]);
 			});
 		}
 	});
 
 	if (opts['--']) {
-		argv['--'] = new Array();
-		notFlags.forEach(function (key) {
-			argv['--'].push(key);
-		});
+		argv['--'] = notFlags.slice();
 	} else {
-		notFlags.forEach(function (key) {
-			argv._.push(key);
+		notFlags.forEach(function (k) {
+			argv._.push(k);
 		});
 	}
 
 	return argv;
 };
 
-function hasKey(obj, keys) {
-	var o = obj;
-	keys.slice(0, -1).forEach(function (key) {
-		o = (o[key] || {});
-	});
-
-	var key = keys[keys.length - 1];
-	return key in o;
-}
-
-function setKey(obj, keys, value) {
-	var o = obj;
-	for (var i = 0; i < keys.length - 1; i++) {
-		var key = keys[i];
-		if (key === '__proto__') return;
-		if (o[key] === undefined) o[key] = {};
-		if (o[key] === Object.prototype || o[key] === Number.prototype
-            || o[key] === String.prototype) o[key] = {};
-		if (o[key] === Array.prototype) o[key] = [];
-		o = o[key];
-	}
-
-	var key = keys[keys.length - 1];
-	if (key === '__proto__') return;
-	if (o === Object.prototype || o === Number.prototype
-        || o === String.prototype) o = {};
-	if (o === Array.prototype) o = [];
-	if (o[key] === undefined || typeof o[key] === 'boolean') {
-		o[key] = value;
-	} else if (Array.isArray(o[key])) {
-		o[key].push(value);
-	} else {
-		o[key] = [o[key], value];
-	}
-}
-
-function isNumber(x) {
-	if (typeof x === 'number') return true;
-	if (/^0x[0-9a-f]+$/i.test(x)) return true;
-	return /^[-+]?(?:\d+(?:\.\d*)?|\.\d+)(e[-+]?\d+)?$/.test(x);
-}
-
diff --git a/test/all_bool.js b/test/all_bool.js
index 3df5709..bc47041 100644
--- a/test/all_bool.js
+++ b/test/all_bool.js
@@ -1,14 +1,16 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
 test('flag boolean true (default all --args to boolean)', function (t) {
 	var argv = parse(['moo', '--honk', 'cow'], {
-		boolean: true
+		boolean: true,
 	});
 
 	t.deepEqual(argv, {
 		honk: true,
-		_: ['moo', 'cow']
+		_: ['moo', 'cow'],
 	});
 
 	t.deepEqual(typeof argv.honk, 'boolean');
@@ -17,14 +19,14 @@ test('flag boolean true (default all --args to boolean)', function (t) {
 
 test('flag boolean true only affects double hyphen arguments without equals signs', function (t) {
 	var argv = parse(['moo', '--honk', 'cow', '-p', '55', '--tacos=good'], {
-		boolean: true
+		boolean: true,
 	});
 
 	t.deepEqual(argv, {
 		_: ['moo', 'cow'],
 		honk: true,
 		p: 55,
-		tacos: 'good'
+		tacos: 'good',
 	});
 
 	t.deepEqual(typeof argv.honk, 'boolean');
diff --git a/test/bool.js b/test/bool.js
index c5f15e3..42f4c2c 100644
--- a/test/bool.js
+++ b/test/bool.js
@@ -1,16 +1,18 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
 test('flag boolean default false', function (t) {
 	var argv = parse(['moo'], {
 		boolean: ['t', 'verbose'],
-		default: { verbose: false, t: false }
+		default: { verbose: false, t: false },
 	});
 
 	t.deepEqual(argv, {
 		verbose: false,
 		t: false,
-		_: ['moo']
+		_: ['moo'],
 	});
 
 	t.deepEqual(typeof argv.verbose, 'boolean');
@@ -21,14 +23,14 @@ test('flag boolean default false', function (t) {
 
 test('boolean groups', function (t) {
 	var argv = parse(['-x', '-z', 'one', 'two', 'three'], {
-		boolean: ['x', 'y', 'z']
+		boolean: ['x', 'y', 'z'],
 	});
 
 	t.deepEqual(argv, {
 		x: true,
 		y: false,
 		z: true,
-		_: ['one', 'two', 'three']
+		_: ['one', 'two', 'three'],
 	});
 
 	t.deepEqual(typeof argv.x, 'boolean');
@@ -39,21 +41,19 @@ test('boolean groups', function (t) {
 test('boolean and alias with chainable api', function (t) {
 	var aliased = ['-h', 'derp'];
 	var regular = ['--herp', 'derp'];
-	var opts = {
-		herp: { alias: 'h', boolean: true }
-	};
+
 	var aliasedArgv = parse(aliased, {
 		boolean: 'herp',
-		alias: { h: 'herp' }
+		alias: { h: 'herp' },
 	});
 	var propertyArgv = parse(regular, {
 		boolean: 'herp',
-		alias: { h: 'herp' }
+		alias: { h: 'herp' },
 	});
 	var expected = {
 		herp: true,
 		h: true,
-		'_': ['derp']
+		_: ['derp'],
 	};
 
 	t.same(aliasedArgv, expected);
@@ -65,15 +65,15 @@ test('boolean and alias with options hash', function (t) {
 	var aliased = ['-h', 'derp'];
 	var regular = ['--herp', 'derp'];
 	var opts = {
-		alias: { 'h': 'herp' },
-		boolean: 'herp'
+		alias: { h: 'herp' },
+		boolean: 'herp',
 	};
 	var aliasedArgv = parse(aliased, opts);
 	var propertyArgv = parse(regular, opts);
 	var expected = {
 		herp: true,
 		h: true,
-		'_': ['derp']
+		_: ['derp'],
 	};
 	t.same(aliasedArgv, expected);
 	t.same(propertyArgv, expected);
@@ -85,14 +85,14 @@ test('boolean and alias using explicit true', function (t) {
 	var regular = ['--herp', 'true'];
 	var opts = {
 		alias: { h: 'herp' },
-		boolean: 'h'
+		boolean: 'h',
 	};
 	var aliasedArgv = parse(aliased, opts);
 	var propertyArgv = parse(regular, opts);
 	var expected = {
 		herp: true,
 		h: true,
-		'_': []
+		_: [],
 	};
 
 	t.same(aliasedArgv, expected);
@@ -103,14 +103,14 @@ test('boolean and alias using explicit true', function (t) {
 // regression, see https://github.com/substack/node-optimist/issues/71
 test('boolean and --x=true', function (t) {
 	var parsed = parse(['--boool', '--other=true'], {
-		boolean: 'boool'
+		boolean: 'boool',
 	});
 
 	t.same(parsed.boool, true);
 	t.same(parsed.other, 'true');
 
 	parsed = parse(['--boool', '--other=false'], {
-		boolean: 'boool'
+		boolean: 'boool',
 	});
 
 	t.same(parsed.boool, true);
diff --git a/test/dash.js b/test/dash.js
index e61a079..7c897d4 100644
--- a/test/dash.js
+++ b/test/dash.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
diff --git a/test/default_bool.js b/test/default_bool.js
index d25dae7..ce93557 100644
--- a/test/default_bool.js
+++ b/test/default_bool.js
@@ -1,10 +1,12 @@
+'use strict';
+
 var test = require('tape');
 var parse = require('../');
 
 test('boolean default true', function (t) {
 	var argv = parse([], {
 		boolean: 'sometrue',
-		default: { sometrue: true }
+		default: { sometrue: true },
 	});
 	t.equal(argv.sometrue, true);
 	t.end();
@@ -13,7 +15,7 @@ test('boolean default true', function (t) {
 test('boolean default false', function (t) {
 	var argv = parse([], {
 		boolean: 'somefalse',
-		default: { somefalse: false }
+		default: { somefalse: false },
 	});
 	t.equal(argv.somefalse, false);
 	t.end();
diff --git a/test/dotted.js b/test/dotted.js
index ed9e9d2..126ff03 100644
--- a/test/dotted.js
+++ b/test/dotted.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
diff --git a/test/long.js b/test/long.js
index 99fe947..9fef51f 100644
--- a/test/long.js
+++ b/test/long.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var test = require('tape');
 var parse = require('../');
 
diff --git a/test/num.js b/test/num.js
index 2075efe..074393e 100644
--- a/test/num.js
+++ b/test/num.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
@@ -8,7 +10,7 @@ test('nums', function (t) {
 		'-z', '1e7',
 		'-w', '10f',
 		'--hex', '0xdeadbeef',
-		'789'
+		'789',
 	]);
 	t.deepEqual(argv, {
 		x: 1234,
@@ -16,7 +18,7 @@ test('nums', function (t) {
 		z: 1e7,
 		w: '10f',
 		hex: 0xdeadbeef,
-		_: [789]
+		_: [789],
 	});
 	t.deepEqual(typeof argv.x, 'number');
 	t.deepEqual(typeof argv.y, 'number');
diff --git a/test/parse.js b/test/parse.js
index 3eee946..f88c816 100644
--- a/test/parse.js
+++ b/test/parse.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
@@ -22,7 +24,7 @@ test('comprehensive', function (t) {
 			'-h', 'awesome', '--multi=quux',
 			'--key', 'value',
 			'-b', '--bool', '--no-meep', '--multi=baz',
-			'--', '--not-a-flag', 'eek'
+			'--', '--not-a-flag', 'eek',
 		]),
 		{
 			c: true,
@@ -36,7 +38,7 @@ test('comprehensive', function (t) {
 			multi: ['quux', 'baz'],
 			meep: false,
 			name: 'meowmers',
-			_: ['bare', '--not-a-flag', 'eek']
+			_: ['bare', '--not-a-flag', 'eek'],
 		}
 	);
 	t.end();
@@ -52,13 +54,13 @@ test('flag boolean', function (t) {
 test('flag boolean value', function (t) {
 	var argv = parse(['--verbose', 'false', 'moo', '-t', 'true'], {
 		boolean: ['t', 'verbose'],
-		default: { verbose: true }
+		default: { verbose: true },
 	});
 
 	t.deepEqual(argv, {
 		verbose: false,
 		t: true,
-		_: ['moo']
+		_: ['moo'],
 	});
 
 	t.deepEqual(typeof argv.verbose, 'boolean');
@@ -67,15 +69,15 @@ test('flag boolean value', function (t) {
 });
 
 test('newlines in params', function (t) {
-	var args = parse(['-s', "X\nX"])
-	t.deepEqual(args, { _: [], s: "X\nX" });
+	var args = parse(['-s', 'X\nX']);
+	t.deepEqual(args, { _: [], s: 'X\nX' });
 
 	// reproduce in bash:
 	// VALUE="new
 	// line"
 	// node program.js --s="$VALUE"
-	args = parse(["--s=X\nX"])
-	t.deepEqual(args, { _: [], s: "X\nX" });
+	args = parse(['--s=X\nX']);
+	t.deepEqual(args, { _: [], s: 'X\nX' });
 	t.end();
 });
 
@@ -110,7 +112,7 @@ test('empty strings', function (t) {
 	t.equal(typeof str, 'string');
 
 	var letters = parse(['-art'], {
-		string: ['a', 't']
+		string: ['a', 't'],
 	});
 
 	t.equal(letters.a, '');
@@ -123,7 +125,7 @@ test('empty strings', function (t) {
 test('string and alias', function (t) {
 	var x = parse(['--str', '000123'], {
 		string: 's',
-		alias: { s: 'str' }
+		alias: { s: 'str' },
 	});
 
 	t.equal(x.str, '000123');
@@ -133,7 +135,7 @@ test('string and alias', function (t) {
 
 	var y = parse(['-s', '000123'], {
 		string: 'str',
-		alias: { str: 's' }
+		alias: { str: 's' },
 	});
 
 	t.equal(y.str, '000123');
@@ -157,7 +159,7 @@ test('slashBreak', function (t) {
 
 test('alias', function (t) {
 	var argv = parse(['-f', '11', '--zoom', '55'], {
-		alias: { z: 'zoom' }
+		alias: { z: 'zoom' },
 	});
 	t.equal(argv.zoom, 55);
 	t.equal(argv.z, argv.zoom);
@@ -167,7 +169,7 @@ test('alias', function (t) {
 
 test('multiAlias', function (t) {
 	var argv = parse(['-f', '11', '--zoom', '55'], {
-		alias: { z: ['zm', 'zoom'] }
+		alias: { z: ['zm', 'zoom'] },
 	});
 	t.equal(argv.zoom, 55);
 	t.equal(argv.z, argv.zoom);
@@ -180,7 +182,7 @@ test('nested dotted objects', function (t) {
 	var argv = parse([
 		'--foo.bar', '3', '--foo.baz', '4',
 		'--foo.quux.quibble', '5', '--foo.quux.o_O',
-		'--beep.boop'
+		'--beep.boop',
 	]);
 
 	t.same(argv.foo, {
@@ -188,8 +190,8 @@ test('nested dotted objects', function (t) {
 		baz: 4,
 		quux: {
 			quibble: 5,
-			o_O: true
-		}
+			o_O: true,
+		},
 	});
 	t.same(argv.beep, { boop: true });
 	t.end();
diff --git a/test/parse_modified.js b/test/parse_modified.js
index 3bcad6a..9a3d298 100644
--- a/test/parse_modified.js
+++ b/test/parse_modified.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
diff --git a/test/proto.js b/test/proto.js
index a97e133..589efd7 100644
--- a/test/proto.js
+++ b/test/proto.js
@@ -1,6 +1,10 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
+/* eslint no-proto: 0 */
+
 test('proto pollution', function (t) {
 	var argv = parse(['--__proto__.x', '123']);
 	t.equal({}.x, undefined);
diff --git a/test/short.js b/test/short.js
index d65dc08..4a7b843 100644
--- a/test/short.js
+++ b/test/short.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');
 
@@ -49,7 +51,7 @@ test('mixed short bool and capture', function (t) {
 		parse(['-h', 'localhost', '-fp', '555', 'script.js']),
 		{
 			f: true, p: 555, h: 'localhost',
-			_: ['script.js']
+			_: ['script.js'],
 		}
 	);
 	t.end();
@@ -60,7 +62,7 @@ test('short and long', function (t) {
 		parse(['-h', 'localhost', '-fp', '555', 'script.js']),
 		{
 			f: true, p: 555, h: 'localhost',
-			_: ['script.js']
+			_: ['script.js'],
 		}
 	);
 	t.end();
diff --git a/test/whitespace.js b/test/whitespace.js
index e79c482..4fdaf1d 100644
--- a/test/whitespace.js
+++ b/test/whitespace.js
@@ -1,3 +1,5 @@
+'use strict';
+
 var parse = require('../');
 var test = require('tape');