diff --git a/package.json b/package.json
index 718909d..9e7b3d3 100644
--- a/package.json
+++ b/package.json
@@ -46,9 +46,6 @@
 		"typeguards",
 		"types"
 	],
-	"dependencies": {
-		"type-fest": "^0.16.0"
-	},
 	"devDependencies": {
 		"@sindresorhus/tsconfig": "^0.7.0",
 		"@types/jsdom": "^16.1.0",
diff --git a/source/index.ts b/source/index.ts
index 86ba271..f8c4e6f 100644
--- a/source/index.ts
+++ b/source/index.ts
@@ -2,7 +2,7 @@
 /// <reference lib="dom"/>
 /// <reference types="node"/>
 
-import {Class, TypedArray, ObservableLike, Primitive} from 'type-fest';
+import {Class, TypedArray, ObservableLike, Primitive} from './types';
 
 const typedArrayTypeNames = [
 	'Int8Array',
diff --git a/source/types.ts b/source/types.ts
new file mode 100644
index 0000000..dcae015
--- /dev/null
+++ b/source/types.ts
@@ -0,0 +1,47 @@
+/**
+Matches any [primitive value](https://developer.mozilla.org/en-US/docs/Glossary/Primitive).
+*/
+export type Primitive =
+	| null
+	| undefined
+	| string
+	| number
+	| boolean
+	| symbol
+	| bigint;
+
+// TODO: Remove the `= unknown` sometime  in the future when most users are on TS 3.5 as it's now the default
+/**
+Matches a [`class` constructor](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes).
+*/
+export type Class<T = unknown, Arguments extends any[] = any[]> = new (...arguments_: Arguments) => T;
+
+/**
+Matches any [typed array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray), like `Uint8Array` or `Float64Array`.
+*/
+export type TypedArray =
+	| Int8Array
+	| Uint8Array
+	| Uint8ClampedArray
+	| Int16Array
+	| Uint16Array
+	| Int32Array
+	| Uint32Array
+	| Float32Array
+	| Float64Array
+	| BigInt64Array
+	| BigUint64Array;
+
+declare global {
+	interface SymbolConstructor {
+		readonly observable: symbol;
+	}
+}
+
+/**
+Matches a value that is like an [Observable](https://github.com/tc39/proposal-observable).
+*/
+export interface ObservableLike {
+	subscribe(observer: (value: unknown) => void): void;
+	[Symbol.observable](): ObservableLike;
+}