diff --git a/types/deep-extend/deep-extend-tests.ts b/types/deep-extend/deep-extend-tests.ts
index c8b1cf7e5e..8d2272255d 100644
--- a/types/deep-extend/deep-extend-tests.ts
+++ b/types/deep-extend/deep-extend-tests.ts
@@ -35,3 +35,4 @@ deepExtend(obj1, obj1, obj1, obj1, obj1, obj1); // More than 5 arguments
 deepExtend({ a: 1 }, { b: true }); // $ExpectType { a: number; } & { b: boolean; }
 // @ts-expect-error
 deepExtend({ a: 1 }, 1);
+deepExtend({ a: 1 }); // $ExpectType { a: number; }
diff --git a/types/deep-extend/index.d.ts b/types/deep-extend/index.d.ts
index 5ce316eff4..3158bf09db 100644
--- a/types/deep-extend/index.d.ts
+++ b/types/deep-extend/index.d.ts
@@ -1,9 +1,11 @@
-// Type definitions for deep-extend 0.4
+// Type definitions for deep-extend 0.6
 // Project: https://github.com/unclechu/node-deep-extend
 // Definitions by: rhysd <https://github.com/rhysd>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// Minimum TypeScript Version: 3.9
 
 /** Recursive object extending. */
+declare function deepExtend<T extends object>(target: T): T;
 declare function deepExtend<T extends object, U extends object>(target: T, source: U): T & U;
 declare function deepExtend<T extends object, U extends object, V extends object>(
     target: T,