diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index b1898ec1..bc5ab99a 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -19,7 +19,7 @@ class AsyncStorageFactory {
 
   static create<M = EmptyStorageModel>(
     storage: IStorageBackend,
-    opts: FactoryOptions | null = null,
+    opts?: FactoryOptions,
   ) {
     return new AsyncStorage<M, IStorageBackend<M>>(
       storage,
diff --git a/packages/core/types/index.d.ts b/packages/core/types/index.d.ts
index c2d186e2..6a6c3427 100644
--- a/packages/core/types/index.d.ts
+++ b/packages/core/types/index.d.ts
@@ -13,7 +13,7 @@
 export default class AsyncStorageFactory {
   static create<M = EmptyStorageModel>(
     storage: IStorageBackend,
-    opts: FactoryOptions,
+    opts?: FactoryOptions,
   ): AsyncStorage<M, IStorageBackend<M>>;
 }