diff --git a/packages/commerce/src/schemas/cart.ts b/packages/commerce/src/schemas/cart.ts
index 298b46c19..000b53faf 100644
--- a/packages/commerce/src/schemas/cart.ts
+++ b/packages/commerce/src/schemas/cart.ts
@@ -11,7 +11,7 @@ export const cartItemBodySchema = z.object({
 })
 
 export const addItemBodySchema = z.object({
-  cartId: z.string(),
+  cartId: z.string().optional(),
   item: cartItemBodySchema,
 })
 
diff --git a/packages/commerce/src/types/cart.ts b/packages/commerce/src/types/cart.ts
index 487d74679..58a5b9b55 100644
--- a/packages/commerce/src/types/cart.ts
+++ b/packages/commerce/src/types/cart.ts
@@ -251,7 +251,7 @@ export type GetCartHandler = GetCartHook & {
 }
 
 export type AddItemHandler = AddItemHook & {
-  body: { cartId: string }
+  body: { cartId?: string }
 }
 
 export type UpdateItemHandler = UpdateItemHook & {