diff --git a/src/js/core/directives/ui-grid-render-container.js b/src/js/core/directives/ui-grid-render-container.js
index c807274ef0..241515bec7 100644
--- a/src/js/core/directives/ui-grid-render-container.js
+++ b/src/js/core/directives/ui-grid-render-container.js
@@ -75,12 +75,10 @@
 
                 scrollTop = containerCtrl.viewport[0].scrollTop;
 
-                var scrollCount = scrollTop + scrollYAmount;
                 // Get the scroll percentage
-                var scrollYPercentage = scrollCount / rowContainer.getVerticalScrollLength();
+                var scrollYPercentage = (scrollTop + scrollYAmount) / rowContainer.getVerticalScrollLength();
 
                 // Keep scrollPercentage within the range 0-1.
-                if (scrollCount < 0 && rowContainer.getVerticalScrollLength() < 0) { scrollYPercentage = 0; }
                 if (scrollYPercentage < 0) { scrollYPercentage = 0; }
                 else if (scrollYPercentage > 1) { scrollYPercentage = 1; }
 
@@ -101,7 +99,8 @@
               }
 
               // Let the parent container scroll if the grid is already at the top/bottom
-              if ((event.deltaY !== 0 && (scrollEvent.atTop(scrollTop) || scrollEvent.atBottom(scrollTop))) ||
+              if (rowContainer.getVerticalScrollLength() < 0 ||
+                  (event.deltaY !== 0 && (scrollEvent.atTop(scrollTop) || scrollEvent.atBottom(scrollTop))) ||
                   (event.deltaX !== 0 && (scrollEvent.atLeft(scrollLeft) || scrollEvent.atRight(scrollLeft)))) {
                 //parent controller scrolls
               }