diff --git a/coders/miff.c b/coders/miff.c
index fcfa21f..c53d8d8 100644
--- a/coders/miff.c
+++ b/coders/miff.c
@@ -1209,7 +1209,7 @@
     packet_size=(size_t) (quantum_info->depth/8);
     if (image->storage_class == DirectClass)
       packet_size=(size_t) (3*quantum_info->depth/8);
-    if (image->type == GrayscaleType)
+    if ((image->type == BilevelType) || (image->type == GrayscaleType))
       packet_size=quantum_info->depth/8;
     if (image->matte != MagickFalse)
       packet_size+=quantum_info->depth/8;
@@ -1243,7 +1243,7 @@
         if (image->matte != MagickFalse)
           quantum_type=IndexAlphaQuantum;
       }
-    if (image->type == GrayscaleType)
+    if ((image->type == BilevelType) || (image->type == GrayscaleType))
       {
         quantum_type=GrayQuantum;
         if (image->matte != MagickFalse)