diff --git a/coders/fax.c b/coders/fax.c
index 78660b8..4490420 100644
--- a/coders/fax.c
+++ b/coders/fax.c
@@ -44,6 +44,7 @@
#include "MagickCore/blob-private.h"
#include "MagickCore/colormap.h"
#include "MagickCore/colorspace.h"
+#include "MagickCore/colorspace-private.h"
#include "MagickCore/exception.h"
#include "MagickCore/exception-private.h"
#include "MagickCore/compress.h"
@@ -323,7 +324,7 @@
/*
Convert MIFF to monochrome.
*/
- if (image->colorspace != RGBColorspace)
+ if (IsRGBColorspace(image->colorspace) == MagickFalse)
(void) TransformImageColorspace(image,RGBColorspace);
status=HuffmanEncodeImage(write_info,image,image);
if (GetNextImageInList(image) == (Image *) NULL)