diff --git a/4chan_x.js b/4chan_x.js
index 40d13ce5a..a9bc8939a 100644
--- a/4chan_x.js
+++ b/4chan_x.js
@@ -183,10 +183,11 @@
       return el;
     },
     move: function(e) {
-      var el;
+      var el, rect;
       el = ui.el;
-      ui.dx = e.clientX - el.offsetLeft;
-      ui.dy = e.clientY - el.offsetTop;
+      rect = el.getBoundingClientRect();
+      ui.dx = e.clientX - rect.left;
+      ui.dy = e.clientY - rect.top;
       ui.width = document.body.clientWidth - el.offsetWidth;
       ui.height = document.body.clientHeight - el.offsetHeight;
       document.addEventListener('mousemove', ui.moveMove, true);
diff --git a/script.coffee b/script.coffee
index abb8bda05..448db70c3 100644
--- a/script.coffee
+++ b/script.coffee
@@ -100,8 +100,10 @@ ui =
   move: (e) ->
     {el} = ui
     #distance from pointer to el edge is constant; calculate it here.
-    ui.dx = e.clientX - el.offsetLeft
-    ui.dy = e.clientY - el.offsetTop
+    # XXX opera reports el.offsetLeft / el.offsetTop as 0
+    rect = el.getBoundingClientRect()
+    ui.dx = e.clientX - rect.left
+    ui.dy = e.clientY - rect.top
     #factor out el from document dimensions
     ui.width  = document.body.clientWidth  - el.offsetWidth
     ui.height = document.body.clientHeight - el.offsetHeight