diff --git a/jquery.slimscroll.js b/jquery.slimscroll.js
index 1c6a53b..37acf84 100644
--- a/jquery.slimscroll.js
+++ b/jquery.slimscroll.js
@@ -223,8 +223,9 @@
           bar.bind("mousedown", function(e) {
             var $doc = $(document);
             isDragg = true;
-            t = parseFloat(bar.css('top'));
-            pageY = e.pageY;
+            const t = parseFloat(bar.css('top'));
+            const pageY = e.pageY;
+            let currTop;
 
             $doc.bind("mousemove.slimscroll", function(e){
               currTop = t + e.pageY - pageY;