diff --git a/coders/mono.c b/coders/mono.c
index c59cdac..41d08ed 100644
--- a/coders/mono.c
+++ b/coders/mono.c
@@ -314,9 +314,7 @@
   status=OpenBlob(image_info,image,WriteBinaryBlobMode,exception);
   if (status == MagickFalse)
     return(status);
-  if ((IssRGBColorspace(image->colorspace) == MagickFalse) &&
-      (IsRGBColorspace(image->colorspace) == MagickFalse) &&
-      (IsImageGray(image,exception) == MagickFalse))
+  if (IssRGBCompatibleColorspace(image->colorspace) == MagickFalse)
     (void) TransformImageColorspace(image,sRGBColorspace,exception);
   /*
     Convert image to a bi-level image.