diff --git a/js/sketch.js b/js/sketch.js
index ed40df3..e80b1a9 100644
--- a/js/sketch.js
+++ b/js/sketch.js
@@ -234,7 +234,7 @@ function mutateFigure(shape) {
       shape.height = shape.height - 0.1 * widthIncrement;
     }
   } else if (shape instanceof Triangle) {
-    shape.width = shape.width - 0.1/duration;
+    shape.width = shape.width - 0.05 * widthIncrement;
 
     if (shape.height < 0.75 * height)
       shape.height = shape.height + 0.01 * widthIncrement;