diff --git a/apps/stetho/stetho.js b/apps/stetho/stetho.js
index 8448422a8..bd943cab7 100644
--- a/apps/stetho/stetho.js
+++ b/apps/stetho/stetho.js
@@ -28,9 +28,9 @@ function readHRM() {
   }
   g.setColor(1,1,1);
   g.lineTo(x,y);
-  console.log("a ", a);
-  freq((a * 1000.0) + 100.0);
-  console.log("freq ", (a * 1000.0) + 100.0);
+  console.log("a ", y);
+  freq((y * 1000.0) + 100.0);
+  console.log("freq ", (y * 1000.0) + 100.0);
   if ((max-min)>0.005) {
     if (4*a > (min+3*max)) { // high
       g.setColor(1,0,0);