diff --git a/Images/common_SliderHoriz.tiff b/Images/common_SliderHoriz.tiff
index 783570023..da89786c5 100644
Binary files a/Images/common_SliderHoriz.tiff and b/Images/common_SliderHoriz.tiff differ
diff --git a/Images/common_SliderVert.tiff b/Images/common_SliderVert.tiff
index d6f246c0e..ea60a6273 100644
Binary files a/Images/common_SliderVert.tiff and b/Images/common_SliderVert.tiff differ
diff --git a/Source/NSSliderCell.m b/Source/NSSliderCell.m
index 16f13a2dd..9a21c813d 100644
--- a/Source/NSSliderCell.m
+++ b/Source/NSSliderCell.m
@@ -181,6 +181,10 @@ DEFINE_RINT_IF_MISSING
 */
 - (void) drawKnob: (NSRect)knobRect
 {
+  NSColor* knobBackgroundColor = [NSColor controlBackgroundColor];
+  [knobBackgroundColor set];
+  NSRectFill (knobRect);
+  
   [_knobCell drawInteriorWithFrame: knobRect inView: _control_view];
 }