https://github.com/ImageMagick/ImageMagick/issues/594
diff --git a/MagickCore/quantize.c b/MagickCore/quantize.c
index 5281ee2..7eb5d75 100644
--- a/MagickCore/quantize.c
+++ b/MagickCore/quantize.c
@@ -110,8 +110,8 @@
%
% Sr, Sg, Sb: Sums of the red, green, and blue component values for all
% pixels not classified at a lower depth. The combination of these sums
-% and n2 will ultimately characterize the mean color of a set of
-% pixels represented by this node.
+% and n2 will ultimately characterize the mean color of a set of pixels
+% represented by this node.
%
% E: the distance squared in RGB space between each pixel contained
% within a node and the nodes' center. This represents the
@@ -1195,7 +1195,7 @@
assert(image->signature == MagickCoreSignature);
if (image->debug != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
- if (image->storage_class != PseudoClass)
+ if (IsPaletteImage(image) == MagickFalse)
return(MagickFalse);
GetQuantizeInfo(&quantize_info);
quantize_info.number_colors=image->colors;
