diff --git a/lib/OpenLayers/Spherical.js b/lib/OpenLayers/Spherical.js
index 74e14a8c75..9f09a46324 100644
--- a/lib/OpenLayers/Spherical.js
+++ b/lib/OpenLayers/Spherical.js
@@ -60,8 +60,8 @@ OpenLayers.Spherical.computeDistanceBetween = function(from, to, radius) {
  * {Float} The heading in degrees.
  */
 OpenLayers.Spherical.computeHeading = function(from, to) {
-    var y = Math.sin(Math.PI * (from.lon - to.lon) / 180) * Math.cos(Math.PI * to.lat / 180);
+    var y = Math.sin(Math.PI * (to.lon - from.lon) / 180) * Math.cos(Math.PI * to.lat / 180);
     var x = Math.cos(Math.PI * from.lat / 180) * Math.sin(Math.PI * to.lat / 180) -
-        Math.sin(Math.PI * from.lat / 180) * Math.cos(Math.PI * to.lat / 180) * Math.cos(Math.PI * (from.lon - to.lon) / 180);
+        Math.sin(Math.PI * from.lat / 180) * Math.cos(Math.PI * to.lat / 180) * Math.cos(Math.PI * (to.lon - from.lon) / 180);
     return 180 * Math.atan2(y, x) / Math.PI;
 };