diff --git a/lib/varDiff.js b/lib/varDiff.js
index 9e1e696..116af32 100644
--- a/lib/varDiff.js
+++ b/lib/varDiff.js
@@ -74,7 +74,7 @@ var varDiff = module.exports = function varDiff(ports){
             return;
 
         var calcInfo = portsCalcInfo[stratumPort];
-        var options = ports[stratumPort];
+        var options = ports[stratumPort].varDiff;
 
         var lastTs;
         var lastRtc;