diff --git a/pkg/api/v1beta1/conversion.go b/pkg/api/v1beta1/conversion.go
index 43a504b256f..31bea4d290b 100644
--- a/pkg/api/v1beta1/conversion.go
+++ b/pkg/api/v1beta1/conversion.go
@@ -710,6 +710,7 @@ func init() {
 			}
 
 			// Produce legacy fields.
+			out.Protocol = ProtocolTCP
 			if len(in.Spec.Ports) > 0 {
 				out.PortName = in.Spec.Ports[0].Name
 				out.Port = in.Spec.Ports[0].Port
diff --git a/pkg/api/v1beta2/conversion.go b/pkg/api/v1beta2/conversion.go
index 731a5fb9709..0300c9c2467 100644
--- a/pkg/api/v1beta2/conversion.go
+++ b/pkg/api/v1beta2/conversion.go
@@ -641,6 +641,7 @@ func init() {
 			}
 
 			// Produce legacy fields.
+			out.Protocol = ProtocolTCP
 			if len(in.Spec.Ports) > 0 {
 				out.PortName = in.Spec.Ports[0].Name
 				out.Port = in.Spec.Ports[0].Port