diff --git a/dockstat.py b/dockstat.py
index 66adeef..b2ae33e 100644
--- a/dockstat.py
+++ b/dockstat.py
@@ -114,15 +114,16 @@ class HTTPHandler(MetricsHandler):
             alert_threshold = int(
                 data['Config']['Labels'].get('io.prometheus.alert.downtime', 3600)
             )
-            starttime = numpy.datetime64(started_at)
+            starttime = numpy.datetime64(started_at, 's').astype('long')
 
             status_gauge.labels(
                 container.id,
                 container.name,
             ).set(int(running))
-            started_at_gauge.labels(container.id, container.name,).set(
-                int(int(starttime) / 1000000000)  # strip nanoseconds
-            )
+            started_at_gauge.labels(
+                container.id,
+                container.name,
+            ).set(starttime)
             exit_code_gauge.labels(
                 container.id,
                 container.name,