diff --git a/src/helper/conninfo/types.ts b/src/helper/conninfo/types.ts
index 3f73efa2..e37a3741 100644
--- a/src/helper/conninfo/types.ts
+++ b/src/helper/conninfo/types.ts
@@ -1,6 +1,6 @@
 import type { Context } from '../../context'
 
-export type AddressType = 'IPv6' | 'IPv4'
+export type AddressType = 'IPv6' | 'IPv4' | undefined
 
 export type NetAddrInfo = {
   /**