diff --git a/core/pkg/ingress/controller/annotations.go b/core/pkg/ingress/controller/annotations.go
index 5a8beeadf..b0ab4218b 100644
--- a/core/pkg/ingress/controller/annotations.go
+++ b/core/pkg/ingress/controller/annotations.go
@@ -109,7 +109,6 @@ const (
 	healthCheck     = "HealthCheck"
 	sslPassthrough  = "SSLPassthrough"
 	sessionAffinity = "SessionAffinity"
-	certificateAuth = "CertificateAuth"
 )
 
 func (e *annotationExtractor) SecureUpstream(ing *extensions.Ingress) bool {