diff --git a/src/components/fx/hover.js b/src/components/fx/hover.js
index 61796f0eb04..0da92d4a893 100644
--- a/src/components/fx/hover.js
+++ b/src/components/fx/hover.js
@@ -279,11 +279,9 @@ function _hover(gd, evt, subplot, noHoverEvent) {
         if(hasUserCalledHover) {
             if('xpx' in evt) xpx = evt.xpx;
             else xpx = xaArray[0]._length / 2;
-            evt.pointerX = xpx + xaArray[0]._offset;
 
             if('ypx' in evt) ypx = evt.ypx;
             else ypx = yaArray[0]._length / 2;
-            evt.pointerY = ypx + yaArray[0]._offset;
         }
         else {
             // fire the beforehover event and quit if it returns false
@@ -300,13 +298,14 @@ function _hover(gd, evt, subplot, noHoverEvent) {
 
             // in case hover was called from mouseout into hovertext,
             // it's possible you're not actually over the plot anymore
-            if(xpx < 0 || xpx > dbb.width || ypx < 0 || ypx > dbb.height) {
+            if(xpx < 0 || xpx > xaArray[0]._length || ypx < 0 || ypx > yaArray[0]._length) {
                 return dragElement.unhoverRaw(gd, evt);
             }
-            evt.pointerX = evt.offsetX;
-            evt.pointerY = evt.offsetY;
         }
 
+        evt.pointerX = xpx + xaArray[0]._offset;
+        evt.pointerY = ypx + yaArray[0]._offset;
+
         if('xval' in evt) xvalArray = helpers.flat(subplots, evt.xval);
         else xvalArray = helpers.p2c(xaArray, xpx);
 
diff --git a/tasks/test_syntax.js b/tasks/test_syntax.js
index bb94efc3faa..31c2d55b34b 100644
--- a/tasks/test_syntax.js
+++ b/tasks/test_syntax.js
@@ -73,6 +73,9 @@ function assertSrcContents() {
     // Forbidden in IE in any context
     var IE_BLACK_LIST = ['classList'];
 
+    // not implemented in FF, or inconsistent with others
+    var FF_BLACK_LIST = ['offsetX', 'offsetY'];
+
     // require'd built-in modules
     var BUILTINS = ['events'];
 
@@ -103,6 +106,9 @@ function assertSrcContents() {
                     else if(IE_SVG_BLACK_LIST.indexOf(lastPart) !== -1) {
                         logs.push(file + ' : contains .' + lastPart + ' (IE failure in SVG)');
                     }
+                    else if(FF_BLACK_LIST.indexOf(lastPart) !== -1) {
+                        logs.push(file + ' : contains .' + lastPart + ' (FF failure)');
+                    }
                 }
                 else if(node.type === 'Identifier' && node.source() === 'getComputedStyle') {
                     if(node.parent.source() !== 'window.getComputedStyle') {