diff --git a/pkg/apis/duck/v1/subscribable_types_conversion_test.go b/pkg/apis/duck/v1/subscribable_types_conversion_test.go
index 42d0c62137c..ce1b1e40ff0 100644
--- a/pkg/apis/duck/v1/subscribable_types_conversion_test.go
+++ b/pkg/apis/duck/v1/subscribable_types_conversion_test.go
@@ -68,3 +68,15 @@ func TestSubscribableStatusConversionBadType(t *testing.T) {
 		t.Errorf("ConvertFrom() = %#v, wanted error", good)
 	}
 }
+
+func TestSubscriberSpecConversionBadType(t *testing.T) {
+	good, bad := &SubscriberSpec{}, &SubscriberSpec{}
+
+	if err := good.ConvertTo(context.Background(), bad); err == nil {
+		t.Errorf("ConvertTo() = %#v, wanted error", bad)
+	}
+
+	if err := good.ConvertFrom(context.Background(), bad); err == nil {
+		t.Errorf("ConvertFrom() = %#v, wanted error", good)
+	}
+}
diff --git a/pkg/apis/duck/v1alpha1/subscribable_types_conversion_test.go b/pkg/apis/duck/v1alpha1/subscribable_types_conversion_test.go
index 81bc0383a4a..d8dc2fc378f 100644
--- a/pkg/apis/duck/v1alpha1/subscribable_types_conversion_test.go
+++ b/pkg/apis/duck/v1alpha1/subscribable_types_conversion_test.go
@@ -250,3 +250,15 @@ func TestSubscribableTypeStatusConversionBadType(t *testing.T) {
 		t.Errorf("ConvertFrom() = %#v, wanted error", good)
 	}
 }
+
+func TestSubscriberSpecStatusConversionBadType(t *testing.T) {
+	good, bad := &SubscriberSpec{}, &SubscriberSpec{}
+
+	if err := good.ConvertTo(context.Background(), bad); err == nil {
+		t.Errorf("ConvertTo() = %#v, wanted error", bad)
+	}
+
+	if err := good.ConvertFrom(context.Background(), bad); err == nil {
+		t.Errorf("ConvertFrom() = %#v, wanted error", good)
+	}
+}
diff --git a/pkg/apis/duck/v1beta1/subscribable_types_conversion_test.go b/pkg/apis/duck/v1beta1/subscribable_types_conversion_test.go
index 6e2547b7e8a..ccb4c9bdeac 100644
--- a/pkg/apis/duck/v1beta1/subscribable_types_conversion_test.go
+++ b/pkg/apis/duck/v1beta1/subscribable_types_conversion_test.go
@@ -301,3 +301,15 @@ func TestSubscribableStatusConversionBadType(t *testing.T) {
 		t.Errorf("ConvertFrom() = %#v, wanted error", good)
 	}
 }
+
+func TestSubscriberSpecConversionBadType(t *testing.T) {
+	good, bad := &SubscriberSpec{}, &SubscriberSpec{}
+
+	if err := good.ConvertTo(context.Background(), bad); err == nil {
+		t.Errorf("ConvertTo() = %#v, wanted error", bad)
+	}
+
+	if err := good.ConvertFrom(context.Background(), bad); err == nil {
+		t.Errorf("ConvertFrom() = %#v, wanted error", good)
+	}
+}