diff --git a/.changeset/wild-monkeys-knock.md b/.changeset/wild-monkeys-knock.md
new file mode 100644
index 0000000..1132f3f
--- /dev/null
+++ b/.changeset/wild-monkeys-knock.md
@@ -0,0 +1,5 @@
+---
+"@softnetics/hono-react-query": patch
+---
+
+Fix: optimistic update type to return undefined if prev does not exists
diff --git a/src/types.ts b/src/types.ts
index 2dc4fa4..2a8bafc 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -229,7 +229,7 @@ export type UseHonoOptimisticUpdateQuery<TApp extends Record<string, any>> = <
 ) => (
   updater: (
     prev: SuccessResponse<InferFunctionReturn<TApp[TPath][TMethod]>> | undefined
-  ) => SuccessResponse<InferFunctionReturn<TApp[TPath][TMethod]>>
+  ) => SuccessResponse<InferFunctionReturn<TApp[TPath][TMethod]>> | undefined
 ) =>
   | {
       previous: SuccessResponse<InferFunctionReturn<TApp[TPath][TMethod]>> | undefined