diff --git a/coders/dpx.c b/coders/dpx.c
index 5d0e524..c2f6e26 100644
--- a/coders/dpx.c
+++ b/coders/dpx.c
@@ -1803,7 +1803,8 @@
     }
   extent=GetBytesPerRow(image->columns,image->matte != MagickFalse ? 4UL : 3UL,
     image->depth,MagickTrue);
-  if ((image_info->type != TrueColorType) && (image->matte == MagickFalse) &&
+  if ((image_info->type != UndefinedColorType) &&
+      (image_info->type != TrueColorType) && (image->matte == MagickFalse) &&
       (IsGrayImage(image,&image->exception) != MagickFalse))
     {
       quantum_type=GrayQuantum;