diff --git a/equivalence_test.go b/equivalence_test.go
index 39d33c1..9ffcc59 100644
--- a/equivalence_test.go
+++ b/equivalence_test.go
@@ -363,6 +363,7 @@ func TestEquivalenceStatsVsMetricsUploads(t *testing.T) {
 }
 
 type fakeMetricsServer struct {
+	monitoringpb.UnimplementedMetricServiceServer
 	mu                           sync.RWMutex
 	stackdriverTimeSeries        []*monitoringpb.CreateTimeSeriesRequest
 	stackdriverMetricDescriptors []*monitoringpb.CreateMetricDescriptorRequest