diff --git a/MagickCore/quantize.c b/MagickCore/quantize.c
index ace5dbb..c445523 100644
--- a/MagickCore/quantize.c
+++ b/MagickCore/quantize.c
@@ -181,6 +181,7 @@
#include "MagickCore/color-private.h"
#include "MagickCore/colormap.h"
#include "MagickCore/colorspace.h"
+#include "MagickCore/colorspace-private.h"
#include "MagickCore/enhance.h"
#include "MagickCore/exception.h"
#include "MagickCore/exception-private.h"
@@ -513,7 +514,7 @@
cube_info->quantize_info->colorspace);
else
if ((image->colorspace != GRAYColorspace) &&
- (image->colorspace != RGBColorspace) &&
+ (IsRGBColorspace(image->colorspace) == MagickFalse) &&
(image->colorspace != CMYColorspace))
(void) TransformImageColorspace((Image *) image,RGBColorspace);
if (AcquireImageColormap(image,cube_info->colors) == MagickFalse)
@@ -800,7 +801,7 @@
else
if ((image->colorspace != GRAYColorspace) &&
(image->colorspace != CMYColorspace) &&
- (image->colorspace != RGBColorspace))
+ (IsRGBColorspace(image->colorspace) == MagickFalse))
(void) TransformImageColorspace((Image *) image,RGBColorspace);
midpoint.red=(MagickRealType) QuantumRange/2.0;
midpoint.green=(MagickRealType) QuantumRange/2.0;