diff --git a/source/index.ts b/source/index.ts
index 748cac0..3f3f1e5 100644
--- a/source/index.ts
+++ b/source/index.ts
@@ -385,9 +385,9 @@ const predicateOnArray = (method: ArrayMethod, predicate: Predicate, values: unk
 is.any = (predicate: Predicate, ...values: unknown[]): boolean => predicateOnArray(Array.prototype.some, predicate, values);
 is.all = (predicate: Predicate, ...values: unknown[]): boolean => predicateOnArray(Array.prototype.every, predicate, values);
 
-const assertType = (condition: boolean, description: string): asserts condition => {
+const assertType = (condition: boolean, description: string, value: unknown): asserts condition => {
 	if (!condition) {
-		throw new TypeError(`Expected value which is "${description}".`);
+		throw new TypeError(`Expected value which is "${description}", received value of type ${is(value)}.`);
 	}
 };
 
@@ -524,90 +524,90 @@ interface Assert {
 
 export const assert: Assert = {
 	// Unknowns.
-	undefined: (value: unknown): asserts value is undefined => assertType(is.undefined(value), TypeName.undefined),
-	string: (value: unknown): asserts value is string => assertType(is.string(value), TypeName.string),
-	number: (value: unknown): asserts value is number => assertType(is.number(value), TypeName.number),
-	bigint: (value: unknown): asserts value is bigint => assertType(is.bigint(value), TypeName.bigint),
+	undefined: (value: unknown): asserts value is undefined => assertType(is.undefined(value), TypeName.undefined, value),
+	string: (value: unknown): asserts value is string => assertType(is.string(value), TypeName.string, value),
+	number: (value: unknown): asserts value is number => assertType(is.number(value), TypeName.number, value),
+	bigint: (value: unknown): asserts value is bigint => assertType(is.bigint(value), TypeName.bigint, value),
 	// eslint-disable-next-line @typescript-eslint/ban-types
-	function_: (value: unknown): asserts value is Function => assertType(is.function_(value), TypeName.Function),
-	null_: (value: unknown): asserts value is null => assertType(is.null_(value), TypeName.null),
-	class_: (value: unknown): asserts value is Class => assertType(is.class_(value), AssertionTypeDescription.class_),
-	boolean: (value: unknown): asserts value is boolean => assertType(is.boolean(value), TypeName.boolean),
-	symbol: (value: unknown): asserts value is symbol => assertType(is.symbol(value), TypeName.symbol),
-	numericString: (value: unknown): asserts value is string => assertType(is.numericString(value), AssertionTypeDescription.numericString),
-	array: <T = unknown>(value: unknown): asserts value is T[] => assertType(is.array(value), TypeName.Array),
-	buffer: (value: unknown): asserts value is Buffer => assertType(is.buffer(value), TypeName.Buffer),
-	nullOrUndefined: (value: unknown): asserts value is null | undefined => assertType(is.nullOrUndefined(value), AssertionTypeDescription.nullOrUndefined),
-	object: (value: unknown): asserts value is Record<string, unknown> => assertType(is.object(value), TypeName.Object),
-	iterable: <T = unknown>(value: unknown): asserts value is Iterable<T> => assertType(is.iterable(value), AssertionTypeDescription.iterable),
-	asyncIterable: <T = unknown>(value: unknown): asserts value is AsyncIterable<T> => assertType(is.asyncIterable(value), AssertionTypeDescription.asyncIterable),
-	generator: (value: unknown): asserts value is Generator => assertType(is.generator(value), TypeName.Generator),
-	nativePromise: <T = unknown>(value: unknown): asserts value is Promise<T> => assertType(is.nativePromise(value), AssertionTypeDescription.nativePromise),
-	promise: <T = unknown>(value: unknown): asserts value is Promise<T> => assertType(is.promise(value), TypeName.Promise),
-	generatorFunction: (value: unknown): asserts value is GeneratorFunction => assertType(is.generatorFunction(value), TypeName.GeneratorFunction),
+	function_: (value: unknown): asserts value is Function => assertType(is.function_(value), TypeName.Function, value),
+	null_: (value: unknown): asserts value is null => assertType(is.null_(value), TypeName.null, value),
+	class_: (value: unknown): asserts value is Class => assertType(is.class_(value), AssertionTypeDescription.class_, value),
+	boolean: (value: unknown): asserts value is boolean => assertType(is.boolean(value), TypeName.boolean, value),
+	symbol: (value: unknown): asserts value is symbol => assertType(is.symbol(value), TypeName.symbol, value),
+	numericString: (value: unknown): asserts value is string => assertType(is.numericString(value), AssertionTypeDescription.numericString, value),
+	array: <T = unknown>(value: unknown): asserts value is T[] => assertType(is.array(value), TypeName.Array, value),
+	buffer: (value: unknown): asserts value is Buffer => assertType(is.buffer(value), TypeName.Buffer, value),
+	nullOrUndefined: (value: unknown): asserts value is null | undefined => assertType(is.nullOrUndefined(value), AssertionTypeDescription.nullOrUndefined, value),
+	object: (value: unknown): asserts value is Record<string, unknown> => assertType(is.object(value), TypeName.Object, value),
+	iterable: <T = unknown>(value: unknown): asserts value is Iterable<T> => assertType(is.iterable(value), AssertionTypeDescription.iterable, value),
+	asyncIterable: <T = unknown>(value: unknown): asserts value is AsyncIterable<T> => assertType(is.asyncIterable(value), AssertionTypeDescription.asyncIterable, value),
+	generator: (value: unknown): asserts value is Generator => assertType(is.generator(value), TypeName.Generator, value),
+	nativePromise: <T = unknown>(value: unknown): asserts value is Promise<T> => assertType(is.nativePromise(value), AssertionTypeDescription.nativePromise, value),
+	promise: <T = unknown>(value: unknown): asserts value is Promise<T> => assertType(is.promise(value), TypeName.Promise, value),
+	generatorFunction: (value: unknown): asserts value is GeneratorFunction => assertType(is.generatorFunction(value), TypeName.GeneratorFunction, value),
 	// eslint-disable-next-line @typescript-eslint/ban-types
-	asyncFunction: (value: unknown): asserts value is Function => assertType(is.asyncFunction(value), TypeName.AsyncFunction),
+	asyncFunction: (value: unknown): asserts value is Function => assertType(is.asyncFunction(value), TypeName.AsyncFunction, value),
 	// eslint-disable-next-line @typescript-eslint/ban-types
-	boundFunction: (value: unknown): asserts value is Function => assertType(is.boundFunction(value), TypeName.Function),
-	regExp: (value: unknown): asserts value is RegExp => assertType(is.regExp(value), TypeName.RegExp),
-	date: (value: unknown): asserts value is Date => assertType(is.date(value), TypeName.Date),
-	error: (value: unknown): asserts value is Error => assertType(is.error(value), TypeName.Error),
-	map: <TKey = unknown, TValue = unknown>(value: unknown): asserts value is Map<TKey, TValue> => assertType(is.map(value), TypeName.Map),
-	set: <T = unknown>(value: unknown): asserts value is Set<T> => assertType(is.set(value), TypeName.Set),
-	weakMap: <TKey extends object = object, TValue = unknown>(value: unknown): asserts value is WeakMap<TKey, TValue> => assertType(is.weakMap(value), TypeName.WeakMap),
-	weakSet: <T extends object = object>(value: unknown): asserts value is WeakSet<T> => assertType(is.weakSet(value), TypeName.WeakSet),
-	int8Array: (value: unknown): asserts value is Int8Array => assertType(is.int8Array(value), TypeName.Int8Array),
-	uint8Array: (value: unknown): asserts value is Uint8Array => assertType(is.uint8Array(value), TypeName.Uint8Array),
-	uint8ClampedArray: (value: unknown): asserts value is Uint8ClampedArray => assertType(is.uint8ClampedArray(value), TypeName.Uint8ClampedArray),
-	int16Array: (value: unknown): asserts value is Int16Array => assertType(is.int16Array(value), TypeName.Int16Array),
-	uint16Array: (value: unknown): asserts value is Uint16Array => assertType(is.uint16Array(value), TypeName.Uint16Array),
-	int32Array: (value: unknown): asserts value is Int32Array => assertType(is.int32Array(value), TypeName.Int32Array),
-	uint32Array: (value: unknown): asserts value is Uint32Array => assertType(is.uint32Array(value), TypeName.Uint32Array),
-	float32Array: (value: unknown): asserts value is Float32Array => assertType(is.float32Array(value), TypeName.Float32Array),
-	float64Array: (value: unknown): asserts value is Float64Array => assertType(is.float64Array(value), TypeName.Float64Array),
-	bigInt64Array: (value: unknown): asserts value is BigInt64Array => assertType(is.bigInt64Array(value), TypeName.BigInt64Array),
-	bigUint64Array: (value: unknown): asserts value is BigUint64Array => assertType(is.bigUint64Array(value), TypeName.BigUint64Array),
-	arrayBuffer: (value: unknown): asserts value is ArrayBuffer => assertType(is.arrayBuffer(value), TypeName.ArrayBuffer),
-	sharedArrayBuffer: (value: unknown): asserts value is SharedArrayBuffer => assertType(is.sharedArrayBuffer(value), TypeName.SharedArrayBuffer),
-	dataView: (value: unknown): asserts value is DataView => assertType(is.dataView(value), TypeName.DataView),
-	urlInstance: (value: unknown): asserts value is URL => assertType(is.urlInstance(value), TypeName.URL),
-	urlString: (value: unknown): asserts value is string => assertType(is.urlString(value), AssertionTypeDescription.urlString),
-	truthy: (value: unknown): asserts value is unknown => assertType(is.truthy(value), AssertionTypeDescription.truthy),
-	falsy: (value: unknown): asserts value is unknown => assertType(is.falsy(value), AssertionTypeDescription.falsy),
-	nan: (value: unknown): asserts value is unknown => assertType(is.nan(value), AssertionTypeDescription.nan),
-	primitive: (value: unknown): asserts value is unknown => assertType(is.primitive(value), AssertionTypeDescription.primitive),
-	integer: (value: unknown): asserts value is number => assertType(is.integer(value), AssertionTypeDescription.integer),
-	safeInteger: (value: unknown): asserts value is number => assertType(is.safeInteger(value), AssertionTypeDescription.safeInteger),
-	plainObject: (value: unknown): asserts value is {[key: string]: unknown} => assertType(is.plainObject(value), AssertionTypeDescription.plainObject),
-	typedArray: (value: unknown): asserts value is TypedArray => assertType(is.typedArray(value), AssertionTypeDescription.typedArray),
-	arrayLike: <T = unknown>(value: unknown): asserts value is ArrayLike<T> => assertType(is.arrayLike(value), AssertionTypeDescription.arrayLike),
-	domElement: (value: unknown): asserts value is Element => assertType(is.domElement(value), AssertionTypeDescription.domElement),
-	observable: (value: unknown): asserts value is ObservableLike => assertType(is.observable(value), TypeName.Observable),
-	nodeStream: (value: unknown): asserts value is NodeStream => assertType(is.nodeStream(value), AssertionTypeDescription.nodeStream),
-	infinite: (value: unknown): asserts value is number => assertType(is.infinite(value), AssertionTypeDescription.infinite),
-	emptyArray: (value: unknown): asserts value is never[] => assertType(is.emptyArray(value), AssertionTypeDescription.emptyArray),
-	nonEmptyArray: (value: unknown): asserts value is unknown[] => assertType(is.nonEmptyArray(value), AssertionTypeDescription.nonEmptyArray),
-	emptyString: (value: unknown): asserts value is '' => assertType(is.emptyString(value), AssertionTypeDescription.emptyString),
-	nonEmptyString: (value: unknown): asserts value is string => assertType(is.nonEmptyString(value), AssertionTypeDescription.nonEmptyString),
-	emptyStringOrWhitespace: (value: unknown): asserts value is string => assertType(is.emptyStringOrWhitespace(value), AssertionTypeDescription.emptyStringOrWhitespace),
-	emptyObject: (value: unknown): asserts value is {[key: string]: never} => assertType(is.emptyObject(value), AssertionTypeDescription.emptyObject),
-	nonEmptyObject: (value: unknown): asserts value is {[key: string]: unknown} => assertType(is.nonEmptyObject(value), AssertionTypeDescription.nonEmptyObject),
-	emptySet: (value: unknown): asserts value is Set<never> => assertType(is.emptySet(value), AssertionTypeDescription.emptySet),
-	nonEmptySet: (value: unknown): asserts value is Set<unknown> => assertType(is.nonEmptySet(value), AssertionTypeDescription.nonEmptySet),
-	emptyMap: (value: unknown): asserts value is Map<never, never> => assertType(is.emptyMap(value), AssertionTypeDescription.emptyMap),
-	nonEmptyMap: (value: unknown): asserts value is Map<unknown, unknown> => assertType(is.nonEmptyMap(value), AssertionTypeDescription.nonEmptyMap),
+	boundFunction: (value: unknown): asserts value is Function => assertType(is.boundFunction(value), TypeName.Function, value),
+	regExp: (value: unknown): asserts value is RegExp => assertType(is.regExp(value), TypeName.RegExp, value),
+	date: (value: unknown): asserts value is Date => assertType(is.date(value), TypeName.Date, value),
+	error: (value: unknown): asserts value is Error => assertType(is.error(value), TypeName.Error, value),
+	map: <TKey = unknown, TValue = unknown>(value: unknown): asserts value is Map<TKey, TValue> => assertType(is.map(value), TypeName.Map, value),
+	set: <T = unknown>(value: unknown): asserts value is Set<T> => assertType(is.set(value), TypeName.Set, value),
+	weakMap: <TKey extends object = object, TValue = unknown>(value: unknown): asserts value is WeakMap<TKey, TValue> => assertType(is.weakMap(value), TypeName.WeakMap, value),
+	weakSet: <T extends object = object>(value: unknown): asserts value is WeakSet<T> => assertType(is.weakSet(value), TypeName.WeakSet, value),
+	int8Array: (value: unknown): asserts value is Int8Array => assertType(is.int8Array(value), TypeName.Int8Array, value),
+	uint8Array: (value: unknown): asserts value is Uint8Array => assertType(is.uint8Array(value), TypeName.Uint8Array, value),
+	uint8ClampedArray: (value: unknown): asserts value is Uint8ClampedArray => assertType(is.uint8ClampedArray(value), TypeName.Uint8ClampedArray, value),
+	int16Array: (value: unknown): asserts value is Int16Array => assertType(is.int16Array(value), TypeName.Int16Array, value),
+	uint16Array: (value: unknown): asserts value is Uint16Array => assertType(is.uint16Array(value), TypeName.Uint16Array, value),
+	int32Array: (value: unknown): asserts value is Int32Array => assertType(is.int32Array(value), TypeName.Int32Array, value),
+	uint32Array: (value: unknown): asserts value is Uint32Array => assertType(is.uint32Array(value), TypeName.Uint32Array, value),
+	float32Array: (value: unknown): asserts value is Float32Array => assertType(is.float32Array(value), TypeName.Float32Array, value),
+	float64Array: (value: unknown): asserts value is Float64Array => assertType(is.float64Array(value), TypeName.Float64Array, value),
+	bigInt64Array: (value: unknown): asserts value is BigInt64Array => assertType(is.bigInt64Array(value), TypeName.BigInt64Array, value),
+	bigUint64Array: (value: unknown): asserts value is BigUint64Array => assertType(is.bigUint64Array(value), TypeName.BigUint64Array, value),
+	arrayBuffer: (value: unknown): asserts value is ArrayBuffer => assertType(is.arrayBuffer(value), TypeName.ArrayBuffer, value),
+	sharedArrayBuffer: (value: unknown): asserts value is SharedArrayBuffer => assertType(is.sharedArrayBuffer(value), TypeName.SharedArrayBuffer, value),
+	dataView: (value: unknown): asserts value is DataView => assertType(is.dataView(value), TypeName.DataView, value),
+	urlInstance: (value: unknown): asserts value is URL => assertType(is.urlInstance(value), TypeName.URL, value),
+	urlString: (value: unknown): asserts value is string => assertType(is.urlString(value), AssertionTypeDescription.urlString, value),
+	truthy: (value: unknown): asserts value is unknown => assertType(is.truthy(value), AssertionTypeDescription.truthy, value),
+	falsy: (value: unknown): asserts value is unknown => assertType(is.falsy(value), AssertionTypeDescription.falsy, value),
+	nan: (value: unknown): asserts value is unknown => assertType(is.nan(value), AssertionTypeDescription.nan, value),
+	primitive: (value: unknown): asserts value is unknown => assertType(is.primitive(value), AssertionTypeDescription.primitive, value),
+	integer: (value: unknown): asserts value is number => assertType(is.integer(value), AssertionTypeDescription.integer, value),
+	safeInteger: (value: unknown): asserts value is number => assertType(is.safeInteger(value), AssertionTypeDescription.safeInteger, value),
+	plainObject: (value: unknown): asserts value is {[key: string]: unknown} => assertType(is.plainObject(value), AssertionTypeDescription.plainObject, value),
+	typedArray: (value: unknown): asserts value is TypedArray => assertType(is.typedArray(value), AssertionTypeDescription.typedArray, value),
+	arrayLike: <T = unknown>(value: unknown): asserts value is ArrayLike<T> => assertType(is.arrayLike(value), AssertionTypeDescription.arrayLike, value),
+	domElement: (value: unknown): asserts value is Element => assertType(is.domElement(value), AssertionTypeDescription.domElement, value),
+	observable: (value: unknown): asserts value is ObservableLike => assertType(is.observable(value), TypeName.Observable, value),
+	nodeStream: (value: unknown): asserts value is NodeStream => assertType(is.nodeStream(value), AssertionTypeDescription.nodeStream, value),
+	infinite: (value: unknown): asserts value is number => assertType(is.infinite(value), AssertionTypeDescription.infinite, value),
+	emptyArray: (value: unknown): asserts value is never[] => assertType(is.emptyArray(value), AssertionTypeDescription.emptyArray, value),
+	nonEmptyArray: (value: unknown): asserts value is unknown[] => assertType(is.nonEmptyArray(value), AssertionTypeDescription.nonEmptyArray, value),
+	emptyString: (value: unknown): asserts value is '' => assertType(is.emptyString(value), AssertionTypeDescription.emptyString, value),
+	nonEmptyString: (value: unknown): asserts value is string => assertType(is.nonEmptyString(value), AssertionTypeDescription.nonEmptyString, value),
+	emptyStringOrWhitespace: (value: unknown): asserts value is string => assertType(is.emptyStringOrWhitespace(value), AssertionTypeDescription.emptyStringOrWhitespace, value),
+	emptyObject: (value: unknown): asserts value is {[key: string]: never} => assertType(is.emptyObject(value), AssertionTypeDescription.emptyObject, value),
+	nonEmptyObject: (value: unknown): asserts value is {[key: string]: unknown} => assertType(is.nonEmptyObject(value), AssertionTypeDescription.nonEmptyObject, value),
+	emptySet: (value: unknown): asserts value is Set<never> => assertType(is.emptySet(value), AssertionTypeDescription.emptySet, value),
+	nonEmptySet: (value: unknown): asserts value is Set<unknown> => assertType(is.nonEmptySet(value), AssertionTypeDescription.nonEmptySet, value),
+	emptyMap: (value: unknown): asserts value is Map<never, never> => assertType(is.emptyMap(value), AssertionTypeDescription.emptyMap, value),
+	nonEmptyMap: (value: unknown): asserts value is Map<unknown, unknown> => assertType(is.nonEmptyMap(value), AssertionTypeDescription.nonEmptyMap, value),
 
 	// Numbers.
-	evenInteger: (value: number): asserts value is number => assertType(is.evenInteger(value), AssertionTypeDescription.evenInteger),
-	oddInteger: (value: number): asserts value is number => assertType(is.oddInteger(value), AssertionTypeDescription.oddInteger),
+	evenInteger: (value: number): asserts value is number => assertType(is.evenInteger(value), AssertionTypeDescription.evenInteger, value),
+	oddInteger: (value: number): asserts value is number => assertType(is.oddInteger(value), AssertionTypeDescription.oddInteger, value),
 
 	// Two arguments.
-	directInstanceOf: <T>(instance: unknown, class_: Class<T>): asserts instance is T => assertType(is.directInstanceOf(instance, class_), AssertionTypeDescription.directInstanceOf),
-	inRange: (value: number, range: number | number[]): asserts value is number => assertType(is.inRange(value, range), AssertionTypeDescription.inRange),
+	directInstanceOf: <T>(instance: unknown, class_: Class<T>): asserts instance is T => assertType(is.directInstanceOf(instance, class_), AssertionTypeDescription.directInstanceOf, instance),
+	inRange: (value: number, range: number | number[]): asserts value is number => assertType(is.inRange(value, range), AssertionTypeDescription.inRange, value),
 
 	// Variadic functions.
-	any: (predicate: Predicate, ...values: unknown[]): void | never => assertType(is.any(predicate, ...values), AssertionTypeDescription.any),
-	all: (predicate: Predicate, ...values: unknown[]): void | never => assertType(is.all(predicate, ...values), AssertionTypeDescription.all)
+	any: (predicate: Predicate, ...values: unknown[]): void | never => assertType(is.any(predicate, ...values), AssertionTypeDescription.any, values),
+	all: (predicate: Predicate, ...values: unknown[]): void | never => assertType(is.all(predicate, ...values), AssertionTypeDescription.all, values)
 };
 
 // Some few keywords are reserved, but we'll populate them for Node.js users
diff --git a/test/test.ts b/test/test.ts
index a046699..6e6c4be 100644
--- a/test/test.ts
+++ b/test/test.ts
@@ -25,8 +25,8 @@ interface Test {
 	is(value: unknown): boolean;
 }
 
-const invertAssertThrow = (description: string, fn: () => void | never): void | never => {
-	const expectedAssertErrorMessage = `Expected value which is "${description}".`;
+const invertAssertThrow = (description: string, fn: () => void | never, value: unknown): void | never => {
+	const expectedAssertErrorMessage = `Expected value which is "${description}", received value of type ${is(value)}.`;
 
 	try {
 		fn();
@@ -481,7 +481,7 @@ const types = new Map<string, Test>([
 	}],
 	['non-domElements', {
 		is: value => !is.domElement(value),
-		assert: (value: unknown) => invertAssertThrow(AssertionTypeDescription.domElement, () => assert.domElement(value)),
+		assert: (value: unknown) => invertAssertThrow(AssertionTypeDescription.domElement, () => assert.domElement(value), value),
 		fixtures: [
 			document.createTextNode('data'),
 			document.createProcessingInstruction('xml-stylesheet', 'href="mycss.css" type="text/css"'),
@@ -556,7 +556,7 @@ const testType = (t: ExecutionContext, type: string, exclude?: string[]) => {
 		for (const fixture of fixtures) {
 			assertIs(testIs(fixture), `Value: ${inspect(fixture)}`);
 			const valueType = JSON.stringify(typeDescription ? typeDescription : typename);
-			assertAsserts(() => testAssert(fixture), `Expected value which is ${valueType}.`);
+			assertAsserts(() => testAssert(fixture), `Expected value which is ${valueType}, received value of type ${is(fixture)}.`);
 
 			if (isTypeUnderTest && typename) {
 				t.is(is(fixture), typename);