diff --git a/index.ts b/index.ts
index e7a7b6c..89deea1 100644
--- a/index.ts
+++ b/index.ts
@@ -7,9 +7,10 @@ type ReadOnlyRefObject<T> = {
   readonly current: T;
 };
 
+type UseStateRefValue<T> = [T, Dispatch<SetStateAction<T>>, ReadOnlyRefObject<T>];
 type UseStateRef = {
-  <S>(initialState: S | (() => S)): [S, Dispatch<SetStateAction<S>>, ReadOnlyRefObject<S>];
-  <S = undefined>(): [S | undefined, Dispatch<SetStateAction<S | undefined>>, ReadOnlyRefObject<S | undefined>];
+  <S>(initialState: S | (() => S)): UseStateRefValue<S>;
+  <S = undefined>(): UseStateRefValue<S>;
 };
 
 const useStateRef: UseStateRef = <S>(initialState?: S | (() => S)) => {
@@ -22,7 +23,7 @@ const useStateRef: UseStateRef = <S>(initialState?: S | (() => S)) => {
     setState(ref.current);
   }, []);
 
-  return [state, dispatch, ref];
+  return [state, dispatch, ref] as UseStateRefValue<S>;
 };
 
 export = useStateRef;