diff --git a/src/path/Curve.js b/src/path/Curve.js
index 75d24c28..fb9ac048 100644
--- a/src/path/Curve.js
+++ b/src/path/Curve.js
@@ -761,12 +761,9 @@ statics: /** @lends Curve */{
             c1x = v[2], c1y = v[3],
             c2x = v[4], c2y = v[5],
             p2x = v[6], p2y = v[7];
-        return (3.0 * c1y * p1x - 1.5 * c1y * c2x
-              - 1.5 * c1y * p2x - 3.0 * p1y * c1x
-              - 1.5 * p1y * c2x - 0.5 * p1y * p2x
-              + 1.5 * c2y * p1x + 1.5 * c2y * c1x
-              - 3.0 * c2y * p2x + 0.5 * p2y * p1x
-              + 1.5 * p2y * c1x + 3.0 * p2y * c2x) / 10;
+        return (6 * (p1x*c1y-p1y*c1x+c2x*p2y-p2x*c2y) +
+                3 * (c1x*p2y-c1y*p2x+p1x*c2y-c2x*p1y+c1x*c2y-c1y*c2x) +
+                1 * (p1x*p2y-p1y*p2x)) / 20;
     },
 
     getBounds: function(v) {