diff --git a/tabs/sensors.js b/tabs/sensors.js
index bdff8ed4..aa64bf1d 100644
--- a/tabs/sensors.js
+++ b/tabs/sensors.js
@@ -48,6 +48,7 @@ function initGraphHelpers(selector, sampleNumber, heightDomain) {
         range([0, width]);
 
     helpers.heightScale = d3.scale.linear().
+        clamp(true).
         domain(heightDomain || [1, -1]).
         range([height, 0]);