diff --git a/packages/router-core/src/serializer.ts b/packages/router-core/src/serializer.ts
index 438be56e72..aaa2163cee 100644
--- a/packages/router-core/src/serializer.ts
+++ b/packages/router-core/src/serializer.ts
@@ -5,17 +5,23 @@ export interface StartSerializer {
   decode: <T>(value: T) => T
 }
 
+type JSONLiteral = string | boolean | null | number
+
 export type SerializerStringifyBy<T, TSerializable> = T extends TSerializable
   ? T
-  : T extends (...args: Array<any>) => any
-    ? 'Function is not serializable'
-    : { [K in keyof T]: SerializerStringifyBy<T[K], TSerializable> }
+  : T extends JSONLiteral
+    ? T
+    : T extends (...args: Array<any>) => any
+      ? 'Function is not serializable'
+      : { [K in keyof T]: SerializerStringifyBy<T[K], TSerializable> }
 
 export type SerializerParseBy<T, TSerializable> = T extends TSerializable
   ? T
-  : T extends React.JSX.Element
-    ? ReadableStream
-    : { [K in keyof T]: SerializerParseBy<T[K], TSerializable> }
+  : T extends JSONLiteral
+    ? T
+    : T extends React.JSX.Element
+      ? ReadableStream
+      : { [K in keyof T]: SerializerParseBy<T[K], TSerializable> }
 
 export type Serializable = Date | undefined | Error | FormData | bigint
 
diff --git a/packages/start-client-core/src/tests/createServerMiddleware.test-d.ts b/packages/start-client-core/src/tests/createServerMiddleware.test-d.ts
index 22caa76e3d..f8dfe7d788 100644
--- a/packages/start-client-core/src/tests/createServerMiddleware.test-d.ts
+++ b/packages/start-client-core/src/tests/createServerMiddleware.test-d.ts
@@ -201,7 +201,7 @@ test('createMiddleware merges client context and sends to the server', () => {
       expectTypeOf(result).toEqualTypeOf<{
         'use functions must return the result of next()': true
         context: { a: boolean; b: string; c: number }
-        sendContext: { a: boolean; b: string; c: number; d: number }
+        sendContext: { a: boolean; b: string; c: number; d: 5 }
         headers: HeadersInit
       }>()
 
@@ -215,7 +215,7 @@ test('createMiddleware merges client context and sends to the server', () => {
         a: boolean
         b: string
         c: number
-        d: number
+        d: 5
       }>()
 
       const result = await options.next({
@@ -232,7 +232,7 @@ test('createMiddleware merges client context and sends to the server', () => {
           }
           sendContext: undefined
         }
-        context: { a: boolean; b: string; c: number; d: number; e: string }
+        context: { a: boolean; b: string; c: number; d: 5; e: string }
         sendContext: undefined
       }>()