diff --git a/src/collection.ts b/src/collection.ts
index 4156fe3..a182381 100644
--- a/src/collection.ts
+++ b/src/collection.ts
@@ -83,7 +83,7 @@ import {Key, Object, toObject} from "./collection/toObject";
 export type Collection<T> = {
     [Symbol.iterator](): Iterator<T>
 
-    toObject<K extends Key, V>(this: Collection<[K, V]>): Object<K, V | undefined>
+    toObject<K extends Key, V>(this: Collection<[K, V]>): Object<K, V>
     toArray(): T[]
     toSet(): Set<T>
     toMap<K, V>(this: Collection<[K, V]>): Map<K, V>
diff --git a/src/collection/toObject.ts b/src/collection/toObject.ts
index c2b9304..e113fa3 100644
--- a/src/collection/toObject.ts
+++ b/src/collection/toObject.ts
@@ -1,6 +1,6 @@
 export type Key = keyof any
-export type Object<K extends Key, V> = { [key in K]: V }
+export type Object<K extends Key, V> = { [key in K]?: V }
 
-export function toObject<K extends Key, V>(value: [K, V][]): Object<K, V | undefined> {
-    return Object.fromEntries(value) as Object<K, V | undefined>;
+export function toObject<K extends Key, V>(value: [K, V][]): Object<K, V> {
+    return Object.fromEntries(value) as Object<K, V>;
 }