diff --git a/src/angularjs-gauge.js b/src/angularjs-gauge.js
index 7d8ee35..d874361 100644
--- a/src/angularjs-gauge.js
+++ b/src/angularjs-gauge.js
@@ -351,7 +351,7 @@
                 function watchData(nv, ov) {
                     if (!gauge) return;
                     if (!angular.isDefined(nv) || angular.equals(nv, ov)) return;
-                    gauge.update(nv, ov);
+                    gauge.update(nv, null);
                 }
 
                 function watchOther(nv, ov) {