diff --git a/src/osx/carbon/colordlgosx.mm b/src/osx/carbon/colordlgosx.mm
index a8649d14c7..4f12861d3d 100644
--- a/src/osx/carbon/colordlgosx.mm
+++ b/src/osx/carbon/colordlgosx.mm
@@ -106,6 +106,7 @@ bool wxColourDialog::Create(wxWindow *parent, wxColourData *data)
     NSAutoreleasePool *thePool;
     thePool = [[NSAutoreleasePool alloc] init];
 
+    [[NSColorPanel sharedColorPanel] setShowsAlpha:YES];
     if(m_colourData.GetColour().IsOk())
         [[NSColorPanel sharedColorPanel] setColor:
             [NSColor colorWithCalibratedRed:(CGFloat) (m_colourData.GetColour().Red() / 255.0)