diff --git a/server/service.go b/server/service.go
index b8a699ecb41489d4902c9ab19310f37886becad7..ed5d29a41055d1c4b68ff2068f9c7ceb7d643b97 100644
--- a/server/service.go
+++ b/server/service.go
@@ -31,7 +31,7 @@ var (
 	// group ACLs do not match the current ticket.
 	ErrUnauthorized = errors.New("unauthorized")
 
-	serviceRx = regexp.MustCompile(`^(?:(?:[a-z0-9][-a-z0-9]*\.)+[a-z]{2,4}|localhost)(?::[0-9]{2,5})?(?:/.*)?/$`)
+	serviceRx = regexp.MustCompile(`^(?:(?:[a-z0-9][-a-z0-9]*\.)+[a-z]{2,}|localhost)(?::[0-9]{2,5})?(?:/.*)?/$`)
 )
 
 // LoginService provides the business logic for the SSO server,