diff --git a/README.markdown b/README.markdown
index 583d19e4..492f37f2 100644
--- a/README.markdown
+++ b/README.markdown
@@ -2,18 +2,18 @@
 
 A jQuery plugin that adds cross-browser mouse wheel support.
 
-In order to use the plugin, simply bind the "mousewheel" event to an element. It also provides two helper methods called `mousewheel` and `unmousewheel` that act just like other event helper methods in jQuery. The event callback receives an extra argument which is the normalized "delta" of the mouse wheel. 
+In order to use the plugin, simply bind the "mousewheel" event to an element. It also provides two helper methods called `mousewheel` and `unmousewheel` that act just like other event helper methods in jQuery. The event callback receives three extra arguments which are the normalized "deltas" of the mouse wheel. 
 
 Here is an example of using both the bind and helper method syntax.
 
     // using bind
-    $('#my_elem').bind('mousewheel', function(event, delta) {
-        console.log(delta);
+    $('#my_elem').bind('mousewheel', function(event, delta, deltaX, deltaY) {
+        console.log(delta, deltaX, deltaY);
     });
     
     // using the event helper
-    $('#my_elem').mousewheel(function(event, delta) {
-        console.log(delta);
+    $('#my_elem').mousewheel(function(event, delta, deltaX, deltaY) {
+        console.log(delta, deltaX, deltaY);
     });