diff --git a/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc b/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc
index c6629d3614c1..ad32ce56d6f8 100644
--- a/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc
+++ b/source/extensions/stat_sinks/metrics_service/grpc_metrics_service_impl.cc
@@ -16,6 +16,15 @@ namespace Extensions {
 namespace StatSinks {
 namespace MetricsService {
 
+namespace {
+// TODO(#4160): use TimeSource::systemTime() rather than directly reading the system-clock.
+int64_t getUnixMicrosForNow() {
+  return std::chrono::duration_cast<std::chrono::milliseconds>(
+             std::chrono::system_clock::now().time_since_epoch())
+      .count();
+}
+} // namespace
+
 GrpcMetricsStreamerImpl::GrpcMetricsStreamerImpl(Grpc::AsyncClientFactoryPtr&& factory,
                                                  ThreadLocal::SlotAllocator& tls,
                                                  const LocalInfo::LocalInfo& local_info)
@@ -69,9 +78,7 @@ void MetricsServiceSink::flushCounter(const Stats::Counter& counter) {
   metrics_family->set_type(io::prometheus::client::MetricType::COUNTER);
   metrics_family->set_name(counter.name());
   auto* metric = metrics_family->add_metric();
-  metric->set_timestamp_ms(std::chrono::duration_cast<std::chrono::milliseconds>(
-                               std::chrono::system_clock::now().time_since_epoch())
-                               .count());
+  metric->set_timestamp_ms(getUnixMicrosForNow());
   auto* counter_metric = metric->mutable_counter();
   counter_metric->set_value(counter.value());
 }
@@ -81,9 +88,7 @@ void MetricsServiceSink::flushGauge(const Stats::Gauge& gauge) {
   metrics_family->set_type(io::prometheus::client::MetricType::GAUGE);
   metrics_family->set_name(gauge.name());
   auto* metric = metrics_family->add_metric();
-  metric->set_timestamp_ms(std::chrono::duration_cast<std::chrono::milliseconds>(
-                               std::chrono::system_clock::now().time_since_epoch())
-                               .count());
+  metric->set_timestamp_ms(getUnixMicrosForNow());
   auto* gauage_metric = metric->mutable_gauge();
   gauage_metric->set_value(gauge.value());
 }
@@ -92,9 +97,7 @@ void MetricsServiceSink::flushHistogram(const Stats::ParentHistogram& histogram)
   metrics_family->set_type(io::prometheus::client::MetricType::SUMMARY);
   metrics_family->set_name(histogram.name());
   auto* metric = metrics_family->add_metric();
-  metric->set_timestamp_ms(std::chrono::duration_cast<std::chrono::milliseconds>(
-                               std::chrono::system_clock::now().time_since_epoch())
-                               .count());
+  metric->set_timestamp_ms(getUnixMicrosForNow());
   auto* summary_metric = metric->mutable_summary();
   const Stats::HistogramStatistics& hist_stats = histogram.intervalStatistics();
   for (size_t i = 0; i < hist_stats.supportedQuantiles().size(); i++) {