diff --git a/lib/GraphiteClient.js b/lib/GraphiteClient.js
index 961f125..8343284 100644
--- a/lib/GraphiteClient.js
+++ b/lib/GraphiteClient.js
@@ -59,9 +59,12 @@ GraphiteClient.appendTags = function(flatMetrics, tags) {
 GraphiteClient.prototype.write = function(metrics, timestamp, cb) {
   if (typeof timestamp === 'function') {
     cb = timestamp;
-    timestamp = Date.now();
+    timestamp = null;
   }
 
+  // default timestamp to now
+  timestamp = timestamp || Date.now();
+
   // cutting timestamp for precision up to the second
   timestamp = Math.floor(timestamp / 1000);