diff --git a/source/simplify.d.ts b/source/simplify.d.ts
index 275ec6a92..a456364d2 100644
--- a/source/simplify.d.ts
+++ b/source/simplify.d.ts
@@ -55,4 +55,4 @@ fn(someInterface as Simplify<SomeInterface>); // Good: transform an `interface`
 
 @category Object
 */
-export type Simplify<T> = {[KeyType in keyof T]: T[KeyType]};
+export type Simplify<T> = {[KeyType in keyof T]: T[KeyType]} & {};