diff --git a/MaterialSkin/Controls/MaterialSlider.cs b/MaterialSkin/Controls/MaterialSlider.cs
index 8cd327c9..5d9f2aa2 100644
--- a/MaterialSkin/Controls/MaterialSlider.cs
+++ b/MaterialSkin/Controls/MaterialSlider.cs
@@ -255,10 +255,10 @@ protected override void OnMouseDown(MouseEventArgs e)
         protected override void OnMouseWheel(MouseEventArgs e)
         {
             base.OnMouseWheel(e);
-            if (_valueMax != 0 && (Value + e.Delta / -40) > _valueMax)
+            if (_valueMax != 0 && (Value + e.Delta / 40) > _valueMax)
                 Value = _valueMax;
             else
-                Value += e.Delta/-40;
+                Value += e.Delta / 40;
             onValueChanged?.Invoke(this, _value);
         }