diff --git a/apps/cogclock/app.js b/apps/cogclock/app.js
index 277eadd3a..2734b9a17 100644
--- a/apps/cogclock/app.js
+++ b/apps/cogclock/app.js
@@ -37,6 +37,7 @@ function addTooth(poly, n) {
 }
 
 function drawCog() {
+  g.reset();
   g.drawCircle(x, y, r1);
   let poly = [];
   for(let t = 1; t<=teeth; t++) {