diff --git a/pkg/apis/flagger/v1beta1/canary.go b/pkg/apis/flagger/v1beta1/canary.go
index 22922b70f..8c8c2be2e 100644
--- a/pkg/apis/flagger/v1beta1/canary.go
+++ b/pkg/apis/flagger/v1beta1/canary.go
@@ -254,7 +254,7 @@ type CanaryMetric struct {
 	Interval string `json:"interval,omitempty"`
 
 	// Deprecated: Max value accepted for this metric (replaced by ThresholdRange)
-	Threshold float64 `json:"threshold"`
+	Threshold float64 `json:"threshold,omitempty"`
 
 	// Range value accepted for this metric
 	// +optional