--- a/testing/mochitest/tests/SimpleTest/EventUtils.js
+++ b/testing/mochitest/tests/SimpleTest/EventUtils.js
@@ -403,17 +403,17 @@ function synthesizeMouseAtPoint(left, to
 
 function synthesizeTouchAtPoint(left, top, aEvent, aWindow = window)
 {
   var utils = _getDOMWindowUtils(aWindow);
 
   if (utils) {
     var id = aEvent.id || utils.DEFAULT_TOUCH_POINTER_ID;
     var rx = aEvent.rx || 1;
-    var ry = aEvent.rx || 1;
+    var ry = aEvent.ry || 1;
     var angle = aEvent.angle || 0;
     var force = aEvent.force || 1;
     var modifiers = _parseModifiers(aEvent, aWindow);
 
     if (("type" in aEvent) && aEvent.type) {
       utils.sendTouchEvent(aEvent.type, [id], [left], [top], [rx], [ry], [angle], [force], 1, modifiers);
     }
     else {