diff --git a/lib/knockout.autocomplete.js b/lib/knockout.autocomplete.js
index c79a1e3..72ab0c8 100644
--- a/lib/knockout.autocomplete.js
+++ b/lib/knockout.autocomplete.js
@@ -582,6 +582,8 @@
                 var left = offset.left;
                 var right = left + dropdownWidth;
                 var bottom = null;
+                var scrollTop = window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0;
+                var scrollLeft = window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft || 0;
 
                 if ((mobileSafari && spaceBelow < 600) || (dropdownHeight > spaceBelow)) {
                     // Place above
@@ -591,16 +593,16 @@
                 if (right > $window.width()) {
                     left = Math.max($window.width() - dropdownWidth, 0);
                 } else {
-                    left -= document.body.scrollLeft;
+                    left -= scrollLeft;
                 }
 
                 // Constrain the menu to the viewport
-                if (top < document.body.scrollTop) {
+                if (top < scrollTop) {
                     // constrained by bottom
-                    top = document.body.scrollTop;
+                    top = scrollTop;
                     bottom = $window.height() - (offset.top - 5);
                 } else {
-                    top -= document.body.scrollTop;
+                    top -= scrollTop;
                 }
 
                 if (top + dropdownHeight > windowHeight) {