diff -up cups-1.6.4/backend/ipp.c.ipp-multifile cups-1.6.4/backend/ipp.c
--- cups-1.6.4/backend/ipp.c.ipp-multifile 2013-09-25 14:06:32.027732925 +0100
+++ cups-1.6.4/backend/ipp.c 2013-09-25 14:10:22.134679512 +0100
@@ -1685,7 +1685,10 @@ main(int argc, /* I - Number of comm
ippAddBoolean(request, IPP_TAG_OPERATION, "last-document",
(i + 1) >= num_files);
- if (document_format)
+ if (num_files > 1)
+ ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_MIMETYPE,
+ "document-format", NULL, "application/octet-stream");
+ else if (document_format)
ippAddString(request, IPP_TAG_OPERATION, IPP_TAG_MIMETYPE,
"document-format", NULL, document_format);