diff --git a/types/index.d.ts b/types/index.d.ts
index 0a971c3..1d062b9 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -29,7 +29,7 @@ type ResponseSpecFunc = <T = any>(
   headers?: AxiosHeaders
 ) => MockAdapter;
 
-type NetErr = 'ENOTFOUND' | 'ECONNREFUSED' | 'ECONNRESET' | 'ECONNABORTED' | 'ETIMEDOUT'
+type NetErr = 'ENOTFOUND' | 'ECONNREFUSED' | 'ECONNRESET' | 'ECONNABORTED' | 'ETIMEDOUT' | (string & Record<never, never>)
 
 declare namespace MockAdapter {
   export interface RequestHandler {