diff --git a/pkg/controller/controller.go b/pkg/controller/controller.go
index 6a0ead6d..39c72c37 100644
--- a/pkg/controller/controller.go
+++ b/pkg/controller/controller.go
@@ -345,17 +345,36 @@ func (c *Controller) verifyCanary(canary *flaggerv1.Canary) error {
 }
 
 func verifyNoCrossNamespaceRefs(canary *flaggerv1.Canary) error {
-	if canary.Spec.UpstreamRef != nil && canary.Spec.UpstreamRef.Namespace != canary.Namespace {
-		return fmt.Errorf("can't access gloo upstream %s.%s, cross-namespace references are blocked", canary.Spec.UpstreamRef.Name, canary.Spec.UpstreamRef.Namespace)
+	if canary.Spec.UpstreamRef != nil {
+		// Default to canary namespace if upstreamRef namespace is empty
+		namespace := canary.Spec.UpstreamRef.Namespace
+		if namespace == "" {
+			namespace = canary.Namespace
+		}
+		if namespace != canary.Namespace {
+			return fmt.Errorf("can't access gloo upstream %s.%s, cross-namespace references are blocked", canary.Spec.UpstreamRef.Name, canary.Spec.UpstreamRef.Namespace)
+		}
 	}
 	if canary.Spec.Analysis != nil {
 		for _, metric := range canary.Spec.Analysis.Metrics {
-			if metric.TemplateRef != nil && metric.TemplateRef.Namespace != canary.Namespace {
-				return fmt.Errorf("can't access metric template %s.%s, cross-namespace references are blocked", metric.TemplateRef.Name, metric.TemplateRef.Namespace)
+			if metric.TemplateRef != nil {
+				// Default to canary namespace if templateRef namespace is empty
+				namespace := metric.TemplateRef.Namespace
+				if namespace == "" {
+					namespace = canary.Namespace
+				}
+				if namespace != canary.Namespace {
+					return fmt.Errorf("can't access metric template %s.%s, cross-namespace references are blocked", metric.TemplateRef.Name, metric.TemplateRef.Namespace)
+				}
 			}
 		}
 		for _, alert := range canary.Spec.Analysis.Alerts {
-			if alert.ProviderRef.Namespace != canary.Namespace {
+			// Default to canary namespace if providerRef namespace is empty
+			namespace := alert.ProviderRef.Namespace
+			if namespace == "" {
+				namespace = canary.Namespace
+			}
+			if namespace != canary.Namespace {
 				return fmt.Errorf("can't access alert provider %s.%s, cross-namespace references are blocked", alert.ProviderRef.Name, alert.ProviderRef.Namespace)
 			}
 		}
diff --git a/pkg/controller/controller_test.go b/pkg/controller/controller_test.go
index aa7a1ee4..2676210d 100644
--- a/pkg/controller/controller_test.go
+++ b/pkg/controller/controller_test.go
@@ -70,6 +70,28 @@ func TestController_verifyCanary(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "MetricTemplate in same namespace with no namespace specified should not return an error",
+			canary: flaggerv1.Canary{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "cd-1",
+					Namespace: "default",
+				},
+				Spec: flaggerv1.CanarySpec{
+					Analysis: &flaggerv1.CanaryAnalysis{
+						Metrics: []flaggerv1.CanaryMetric{
+							{
+								TemplateRef: &flaggerv1.CrossNamespaceObjectReference{
+									Name:      "mt-1",
+									Namespace: "",
+								},
+							},
+						},
+					},
+				},
+			},
+			wantErr: false,
+		},
 		{
 			name: "AlertProvider in a different namespace should return an error",
 			canary: flaggerv1.Canary{