diff --git a/README.md b/README.md
index 0d67b8a..ae1188e 100644
--- a/README.md
+++ b/README.md
@@ -54,7 +54,7 @@ classNames({ foo: true, bar: true }); // => 'foo bar'
 classNames('foo', { bar: true, duck: false }, 'baz', { quux: true }); // => 'foo bar baz quux'
 
 // other falsy values are just ignored
-classNames(null, false, 'bar', undefined, 0, 1, { baz: null }, ''); // => 'bar 1'
+classNames(null, false, 'bar', undefined, 0, { baz: null }, ''); // => 'bar'
 ```
 
 Arrays will be recursively flattened as per the rules above:
diff --git a/benchmarks/benchmarks.js b/benchmarks/benchmarks.js
index b80d744..5428c6b 100644
--- a/benchmarks/benchmarks.js
+++ b/benchmarks/benchmarks.js
@@ -33,7 +33,7 @@ const benchmarks = [
 	},
 	{
 		description: 'mix',
-		args: ['one', {two: true, three: false}, {four: 'four', five: true}, 6, {}]
+		args: ['one', {two: true, three: false}, {four: 'four', five: true}, {}]
 	},
 	{
 		description: 'arrays',
diff --git a/bind.js b/bind.js
index 70c342f..eaa1eaa 100644
--- a/bind.js
+++ b/bind.js
@@ -14,7 +14,7 @@ export default function classNames () {
 }
 
 function parseValue (arg) {
-	if (typeof arg === 'string' || typeof arg === 'number') {
+	if (typeof arg === 'string') {
 		return this && this[arg] || arg;
 	}
 
diff --git a/dedupe.js b/dedupe.js
index 6951e84..093c6f0 100644
--- a/dedupe.js
+++ b/dedupe.js
@@ -27,8 +27,6 @@ function appendValue (classSet, arg) {
 		appendArray(classSet, arg);
 	} else if (argType === 'object') {
 		appendObject(classSet, arg);
-	} else if (argType === 'number') {
-		appendNumber(classSet, arg);
 	}
 }
 
@@ -51,10 +49,6 @@ function appendArray (classSet, array) {
 	}
 }
 
-function appendNumber (classSet, num) {
-	classSet[num] = true;
-}
-
 const hasOwn = {}.hasOwnProperty;
 
 function appendObject (classSet, object) {
diff --git a/index.d.ts b/index.d.ts
index 97f52b4..7220bea 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -7,7 +7,7 @@
 //   Sean Kelley <https://github.com/seansfkelley>
 //   Michal Adamczyk <https://github.com/mradamczyk>
 //   Marvin Hagemeister <https://github.com/marvinhagemeister>
-export type Value = string | number | boolean | undefined | null;
+export type Value = string | boolean | undefined | null;
 export type Mapping = Record<string, any>;
 export interface ArgumentArray extends Array<Argument> {}
 export interface ReadonlyArgumentArray extends ReadonlyArray<Argument> {}
diff --git a/index.js b/index.js
index b0bda7a..8915411 100644
--- a/index.js
+++ b/index.js
@@ -14,7 +14,7 @@ export default function classNames () {
 }
 
 function parseValue (arg) {
-	if (typeof arg === 'string' || typeof arg === 'number') {
+	if (typeof arg === 'string') {
 		return arg;
 	}
 
diff --git a/tests/bind.js b/tests/bind.js
index cf5b84b..ba375e6 100644
--- a/tests/bind.js
+++ b/tests/bind.js
@@ -27,7 +27,7 @@ describe('bind', () => {
 		});
 
 		it('joins arrays of class names and ignore falsy values', () => {
-			assert.equal(classNames('a', 0, null, undefined, true, 1, 'b'), 'a 1 b');
+			assert.equal(classNames('a', 0, null, undefined, false, 'b'), 'a b');
 		});
 
 		it('supports heterogenous arguments', () => {
@@ -105,7 +105,7 @@ describe('bind', () => {
 		});
 
 		it('joins arrays of class names and ignore falsy values', () => {
-			assert.equal(classNamesBound('a', 0, null, undefined, true, 1, 'b'), '#a 1 #b');
+			assert.equal(classNamesBound('a', 0, null, undefined, false, 1, 'b'), '#a #b');
 		});
 
 		it('supports heterogenous arguments', () => {
diff --git a/tests/bind.test-d.ts b/tests/bind.test-d.ts
index 71878a4..7211951 100644
--- a/tests/bind.test-d.ts
+++ b/tests/bind.test-d.ts
@@ -22,17 +22,17 @@ bound(null);
 bound(undefined);
 bound(true);
 bound(false);
-bound(42);
 bound({ conditional: true });
 bound({ conditional: {} });
 bound({ conditional: Symbol() });
 bound([]);
-bound([['bar', null, undefined, true, false, 1234]]);
-bound(['bar', null, undefined, true, false, 1234]);
-bound('bar', null, undefined, true, false, 1234);
+bound([['bar', null, undefined, true, false]]);
+bound(['bar', null, undefined, true, false]);
+bound('bar', null, undefined, true, false);
 bound('bar', ['abc', { foo: true }]);
-bound('bar', ['abc', { foo: true }], { def: false, ijk: 1234 });
-bound('abc', 1234, true, false, undefined, null, { foo: true }, ['abc', 1234, true, false, undefined, null, { foo: true }]);
+bound('bar', ['abc', { foo: true }], { def: false });
+bound('abc', true, false, undefined, null, { foo: true }, ['abc', true, false, undefined, null, { foo: true }]);
 bound(foo);
 bound(ifoo);
 expectError(bound(Symbol()));
+expectError(bound(42));
diff --git a/tests/dedupe.js b/tests/dedupe.js
index ac7de52..c1c51d1 100644
--- a/tests/dedupe.js
+++ b/tests/dedupe.js
@@ -23,14 +23,14 @@ describe('dedupe', () => {
 	});
 
 	it('should make sure object with falsy value wipe out previous classes', () => {
-		assert.equal(dedupe('foo foo', 0, null, undefined, true, 1, 'b', { 'foo': false }), '1 b');
+		assert.equal(dedupe('foo foo', 0, null, undefined, false, 'b', { 'foo': false }), 'b');
 		assert.equal(dedupe('foo', 'foobar', 'bar', { foo: false }), 'foobar bar');
 		assert.equal(dedupe('foo', 'foo-bar', 'bar', { foo: false }), 'foo-bar bar');
 		assert.equal(dedupe('foo', '-moz-foo-bar', 'bar', { foo: false }), '-moz-foo-bar bar');
 	});
 
 	it('joins arrays of class names and ignore falsy values', () => {
-		assert.equal(dedupe('a', 0, null, undefined, true, 1, 'b'), '1 a b');
+		assert.equal(dedupe('a', 0, null, undefined, false, 'b'), 'a b');
 	});
 
 	it('supports heterogenous arguments', () => {
diff --git a/tests/dedupe.test-d.ts b/tests/dedupe.test-d.ts
index 693562a..ae4349b 100644
--- a/tests/dedupe.test-d.ts
+++ b/tests/dedupe.test-d.ts
@@ -19,17 +19,17 @@ dedupe(null);
 dedupe(undefined);
 dedupe(true);
 dedupe(false);
-dedupe(42);
 dedupe({ conditional: true });
 dedupe({ conditional: {} });
 dedupe({ conditional: Symbol() });
 dedupe([]);
-dedupe([['bar', null, undefined, true, false, 1234]]);
-dedupe(['bar', null, undefined, true, false, 1234]);
-dedupe('bar', null, undefined, true, false, 1234);
+dedupe([['bar', null, undefined, true, false]]);
+dedupe(['bar', null, undefined, true, false]);
+dedupe('bar', null, undefined, true, false);
 dedupe('bar', ['abc', { foo: true }]);
-dedupe('bar', ['abc', { foo: true }], { def: false, ijk: 1234 });
-dedupe('abc', 1234, true, false, undefined, null, { foo: true }, ['abc', 1234, true, false, undefined, null, { foo: true }]);
+dedupe('bar', ['abc', { foo: true }], { def: false });
+dedupe('abc', true, false, undefined, null, { foo: true }, ['abc', true, false, undefined, null, { foo: true }]);
 dedupe(foo);
 dedupe(ifoo);
 expectError(dedupe(Symbol()));
+expectError(dedupe(42));
diff --git a/tests/index.js b/tests/index.js
index 260b32c..d7f276d 100644
--- a/tests/index.js
+++ b/tests/index.js
@@ -16,7 +16,7 @@ describe('classNames', () => {
 	});
 
 	it('joins arrays of class names and ignore falsy values', () => {
-		assert.equal(classNames('a', 0, null, undefined, true, 1, 'b'), 'a 1 b');
+		assert.equal(classNames('a', 0, null, undefined, false, 'b'), 'a b');
 	});
 
 	it('supports heterogenous arguments', () => {
diff --git a/tests/index.test-d.ts b/tests/index.test-d.ts
index 90b092d..1254943 100644
--- a/tests/index.test-d.ts
+++ b/tests/index.test-d.ts
@@ -19,25 +19,25 @@ classNames(null);
 classNames(undefined);
 classNames(true);
 classNames(false);
-classNames(42);
 classNames({ conditional: true });
 classNames({ conditional: {} });
 classNames({ conditional: Symbol() });
 classNames([]);
-classNames([['bar', null, undefined, true, false, 1234]]);
-classNames(['bar', null, undefined, true, false, 1234]);
-classNames('bar', null, undefined, true, false, 1234);
+classNames([['bar', null, undefined, true, false]]);
+classNames(['bar', null, undefined, true, false]);
+classNames('bar', null, undefined, true, false);
 classNames('bar', ['abc', { foo: true }]);
-classNames('bar', ['abc', { foo: true }], { def: false, ijk: 1234 });
-classNames('abc', 1234, true, false, undefined, null, { foo: true }, ['abc', 1234, true, false, undefined, null, { foo: true }]);
-classNames('abc', 1234, true, false, undefined, null, { foo: true }, ['abc', 1234, true, false, undefined, null, { foo: true }], ['abc', 1234, true, false, undefined, null, { foo: true }] as const);
+classNames('bar', ['abc', { foo: true }], { def: false });
+classNames('abc', true, false, undefined, null, { foo: true }, ['abc', true, false, undefined, null, { foo: true }]);
+classNames('abc', true, false, undefined, null, { foo: true }, ['abc', true, false, undefined, null, { foo: true }], ['abc', 1234, true, false, undefined, null, { foo: true }] as const);
 classNames(foo);
 classNames(ifoo);
 expectError(classNames(Symbol()));
+expectError(classNames(42));
 // should match tests/index.js
 classNames('c', ['a', 'b']);
 classNames('', 'b', {}, '');
-classNames('a', 0, null, undefined, true, 1, 'b');
+classNames('a', null, undefined, true, 'b');
 classNames('a', [[]]);
 classNames('a', []);
 classNames('c', ['a', 'b']);
@@ -48,5 +48,5 @@ classNames(['a', 0, null, undefined, false, true, 'b']);
 classNames(['a', ['b', 'c']]);
 classNames(['a', ['b', ['c', {d: true}]]]);
 classNames(['a', {b: true, c: false}]);
-classNames({a: true}, 'b', 0);
-classNames({}, Infinity, [{}, []]);
+classNames({a: true}, 'b');
+classNames({}, [{}, []]);