diff --git a/src/fastify.ts b/src/fastify.ts
index b27a5af..d080e45 100644
--- a/src/fastify.ts
+++ b/src/fastify.ts
@@ -5,9 +5,9 @@ export type ServiceResult<T = unknown> = {
   successful: boolean;
 };
 
-export type API_Error = {
-  error: string;
-};
+export class API_Error {
+  constructor(public error: string) {}
+}
 
 export abstract class BaseClient {
   private axiosInstance: AxiosInstance;