diff --git a/tests/unit/position/position_core.js b/tests/unit/position/position_core.js
index e03d4c11152..481e92c9046 100644
--- a/tests/unit/position/position_core.js
+++ b/tests/unit/position/position_core.js
@@ -575,7 +575,14 @@ test( "collision: flip, with margin", function() {
 });
 
 test( "within", function() {
-	expect( 6 );
+	expect( 7 );
+
+	collisionTest({
+		within : document
+	}, {
+		top : 10,
+		left : 10
+	}, "within document (bug #9533)");
 
 	collisionTest({
 		within: "#within",
diff --git a/ui/jquery.ui.position.js b/ui/jquery.ui.position.js
index 21c3cef1b19..117858b0433 100644
--- a/ui/jquery.ui.position.js
+++ b/ui/jquery.ui.position.js
@@ -88,8 +88,8 @@ $.position = {
 		return (cachedScrollbarWidth = w1 - w2);
 	},
 	getScrollInfo: function( within ) {
-		var overflowX = within.isWindow ? "" : within.element.css( "overflow-x" ),
-			overflowY = within.isWindow ? "" : within.element.css( "overflow-y" ),
+		var overflowX = within.isWindow || within.isDoc ? "" : within.element.css( "overflow-x" ),
+			overflowY = within.isWindow || within.isDoc ? "" : within.element.css( "overflow-y" ),
 			hasOverflowX = overflowX === "scroll" ||
 				( overflowX === "auto" && within.width < within.element[0].scrollWidth ),
 			hasOverflowY = overflowY === "scroll" ||
@@ -101,10 +101,12 @@ $.position = {
 	},
 	getWithinInfo: function( element ) {
 		var withinElement = $( element || window ),
-			isWindow = $.isWindow( withinElement[0] );
+			isWindow = $.isWindow( withinElement[0] ),
+			isDoc = (!!withinElement[0] && withinElement[0].nodeType === 9);
 		return {
 			element: withinElement,
 			isWindow: isWindow,
+			isDoc: isDoc,
 			offset: withinElement.offset() || { left: 0, top: 0 },
 			scrollLeft: withinElement.scrollLeft(),
 			scrollTop: withinElement.scrollTop(),