diff --git a/types/ungap__weakmap/index.d.ts b/types/ungap__weakmap/index.d.ts
new file mode 100644
index 0000000000..4669d8cbdb
--- /dev/null
+++ b/types/ungap__weakmap/index.d.ts
@@ -0,0 +1,20 @@
+// Type definitions for @ungap/weakmap 0.1
+// Project: https://github.com/ungap/weakmap#readme
+// Definitions by: ExE Boss <https://github.com/ExE-Boss>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+/**
+ * Based on definitions from `lib.es2015.collection` and `lib.es2015.iterable`.
+ */
+declare class WeakMap<K extends object = object, V = any> {
+	constructor(entries?: ReadonlyArray<[K, V]> | null);
+	constructor(iterable: Iterable<[K, V]> | null | undefined);
+
+	delete(key: K): boolean;
+	get(key: K): V | undefined;
+	has(key: K): boolean;
+	set(key: K, value: V): this;
+}
+
+export = WeakMap;
+export as namespace WeakMap;
diff --git a/types/ungap__weakmap/test/weakmap.cjs.test.ts b/types/ungap__weakmap/test/weakmap.cjs.test.ts
new file mode 100644
index 0000000000..61461b9c70
--- /dev/null
+++ b/types/ungap__weakmap/test/weakmap.cjs.test.ts
@@ -0,0 +1,22 @@
+import WeakMap = require('ungap__weakmap');
+
+WeakMap; // $ExpectType typeof WeakMap
+
+// $ExpectType WeakMap<object, any>
+const weakMap = new WeakMap();
+
+weakMap.delete; // $ExpectType (key: object) => boolean
+weakMap.has; // $ExpectType (key: object) => boolean
+weakMap.get; // $ExpectType (key: object) => any
+weakMap.set; // $ExpectType (key: object, value: any) => WeakMap<object, any>
+
+function foo<K extends object, V>(...args: Array<[K, V]>): WeakMap<K, V> {
+	const weakMap = new WeakMap(arguments as Iterable<[K, V]>);
+
+	weakMap.delete; // $ExpectType (key: K) => boolean
+	weakMap.has; // $ExpectType (key: K) => boolean
+	weakMap.get; // $ExpectType (key: K) => V | undefined
+	weakMap.set; // $ExpectType (key: K, value: V) => WeakMap<K, V>
+
+	return weakMap;
+}
diff --git a/types/ungap__weakmap/tsconfig.json b/types/ungap__weakmap/tsconfig.json
new file mode 100644
index 0000000000..14563bc8e6
--- /dev/null
+++ b/types/ungap__weakmap/tsconfig.json
@@ -0,0 +1,19 @@
+{
+	"compilerOptions": {
+		"module": "commonjs",
+		"lib": ["es5", "es2015.iterable"],
+		"noImplicitAny": true,
+		"noImplicitThis": true,
+		"strictFunctionTypes": true,
+		"strictNullChecks": true,
+		"baseUrl": "../",
+		"typeRoots": ["../"],
+		"types": [],
+		"noEmit": true,
+		"forceConsistentCasingInFileNames": true
+	},
+	"files": [
+		"index.d.ts",
+		"test/weakmap.cjs.test.ts"
+	]
+}
diff --git a/types/ungap__weakmap/tslint.json b/types/ungap__weakmap/tslint.json
new file mode 100644
index 0000000000..3db14f85ea
--- /dev/null
+++ b/types/ungap__weakmap/tslint.json
@@ -0,0 +1 @@
+{ "extends": "dtslint/dt.json" }