diff --git a/modules/Slider.js b/modules/Slider.js
index dda5a3bfe..4bf2f8ad0 100644
--- a/modules/Slider.js
+++ b/modules/Slider.js
@@ -44,7 +44,7 @@ try { // for making it possiblie to run the test app in the following catch stat
     o.c._height = o.c.height - 2*totalBorderSize;
     o.c.rounded = o.c.rounded?20:0;
 
-    o.c.STEP_SIZE = (o.c._height-(2*o.c.rounded-7))/o.c.steps;
+    o.c.STEP_SIZE = (o.c._height-(!o.c.rounded?0:(2*o.c.rounded-7)))/o.c.steps;
 
     if (o.c.horizontal) {
       let mediator = o.c._xStart;
@@ -161,7 +161,7 @@ try { // for making it possiblie to run the test app in the following catch stat
         g.setColor(o.c.colorBG).
           fillRect(o.c.hollowRect). // ... and here it's made hollow.
           setColor(0==level?o.c.colorBG:o.c.colorFG).
-          fillRect(o.f.updateBar(2*o.c.rounded-7+level*o.c.STEP_SIZE)); // Here the bar is drawn.
+          fillRect(o.f.updateBar((!o.c.rounded?0:(2*o.c.rounded-7))+level*o.c.STEP_SIZE)); // Here the bar is drawn.
         if (o.c.rounded && level===0) {
           g.setColor(o.c.colorFG).fillCircle(o.c._xStart+o.c._width/2,o.c._yStart+o.c._height-o.c.rounded+2, o.c.rounded-o.c.innerBorderSize);
           g.setColor(o.c.colorBG).fillCircle(o.c._xStart+o.c._width/2,o.c._yStart+o.c._height-o.c.rounded+2, o.c.rounded-o.c.innerBorderSize-2);