diff --git a/index.ts b/index.ts
index c830a9c..4bac146 100644
--- a/index.ts
+++ b/index.ts
@@ -49,7 +49,7 @@ export const TypeBoxValidatorCompiler: FastifySchemaCompiler<TSchema> = ({ schem
  * ```
  */
 export interface TypeBoxTypeProvider extends FastifyTypeProvider {
-  output: this['input'] extends TSchema ? Static<this['input']> : never
+  output: this['input'] extends TSchema ? Static<this['input']> : unknown
 }
 
 /**
diff --git a/types/index.test-d.ts b/types/index.test-d.ts
index ef76c89..9027e68 100644
--- a/types/index.test-d.ts
+++ b/types/index.test-d.ts
@@ -5,6 +5,7 @@ import Fastify, { FastifyInstance, FastifyLoggerInstance, RawReplyDefaultExpress
 
 const fastify = Fastify().withTypeProvider<TypeBoxTypeProvider>()
 expectAssignable<FastifyInstance<RawServerDefault, RawRequestDefaultExpression, RawReplyDefaultExpression, FastifyLoggerInstance, TypeBoxTypeProvider>>(fastify)
+expectAssignable<FastifyInstance>(fastify)
 
 fastify.get('/', {
   schema: {