diff --git a/index.d.ts b/index.d.ts
index e848bff..291c4d0 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1,9 +1,19 @@
-export function diff (originalObj: object, updatedObj: object): object
+type DeepPartial<T> = T extends object ? {
+    [P in keyof T]?: DeepPartial<T[P]>;
+} : T;
 
-export function addedDiff (originalObj: object, updatedObj: object): object
+export function diff <T extends object, J extends object>(originalObj: T, updatedObj: J): DeepPartial<T & J>
 
-export function deletedDiff (originalObj: object, updatedObj: object): object
+export function addedDiff <T extends object, J extends object>(originalObj: T, updatedObj: J): DeepPartial<T & J>
 
-export function updatedDiff (originalObj: object, updatedObj: object): object
+export function deletedDiff <T extends object, J extends object>(originalObj: T, updatedObj: J): DeepPartial<T & J>
 
-export function detailedDiff (originalObj: object, updatedObj: object): object
+export function updatedDiff <T extends object, J extends object>(originalObj: T, updatedObj: J): DeepPartial<T & J>
+
+export interface DetailedDiff<T extends object, J extends object> {
+    added: DeepPartial<T & J>
+    deleted: DeepPartial<T & J>
+    updated: DeepPartial<T & J>
+}
+
+export function detailedDiff <T extends object, J extends object>(originalObj: T, updatedObj: J): DetailedDiff<T & J>