diff --git a/ui/ribbons.js b/ui/ribbons.js
index 7e2fc45e..7e6bc9c9 100755
--- a/ui/ribbons.js
+++ b/ui/ribbons.js
@@ -820,10 +820,10 @@ function prevImage(n){
 
 
 function nextScreenImages(){
-	return nextImage(Math.round(getScreenWidthInImages()))
+	return nextImage(Math.floor(getScreenWidthInImages())-1)
 }
 function prevScreenImages(){
-	return prevImage(Math.round(getScreenWidthInImages()))
+	return prevImage(Math.floor(getScreenWidthInImages())-1)
 }