diff --git a/calculator/calculator.app.js b/calculator/calculator.app.js
index 00dccae..479cfb2 100644
--- a/calculator/calculator.app.js
+++ b/calculator/calculator.app.js
@@ -101,7 +101,7 @@ function drawKey(name, k, selected) {
   g.setColor(color[selected ? 1 : 0]);
   g.setFont('Vector', 20).setFontAlign(0,0);
   g.fillRect(k.xy[0], k.xy[1], k.xy[2], k.xy[3]);
-  g.setColor(-1);
+  g.setColor(0);
   g.drawString(k.val || name, (k.xy[0] + k.xy[2])/2, (k.xy[1] + k.xy[3])/2);
 }