diff --git a/src/influx.rs b/src/influx.rs
index e2f6aea..d6f4c1b 100644
--- a/src/influx.rs
+++ b/src/influx.rs
@@ -207,6 +207,8 @@ impl InfluxWriter {
 
     pub fn dur_nanos(&self, d: Duration) -> i64 { dur_nanos(d) as i64 }
 
+    pub fn dur_nanos_u64(&self, d: Duration) -> u64 { dur_nanos(d).max(0) as u64 }
+
     pub fn tx(&self) -> Sender<Option<OwnedMeasurement>> {
         self.tx.clone()
     }