diff --git a/scm/mu-scm-test.scm b/scm/mu-scm-test.scm
index e45bcc89..bde76488 100644
--- a/scm/mu-scm-test.scm
+++ b/scm/mu-scm-test.scm
@@ -121,10 +121,14 @@
 	  ((index . 2) (content-type . "image/jpeg") (size . 21566) (filename . "custer.jpg")))
       (map (lambda (part) (mime-part->alist part)) (mime-parts msg)))
 
+    (test-equal "mime-part-0" (filename (list-ref (mime-parts msg) 0)))
+    (test-equal "sittingbull.jpg" (filename (list-ref (mime-parts msg) 1)))
+    (test-equal "custer.jpg" (filename (list-ref (mime-parts msg) 2)))
+
     (let* ((part (list-ref (mime-parts msg) 1))
 	   (alist (mime-part->alist part))
 	   (fname (format #f "~a/~a" tmpdir (assoc-ref alist 'filename))))
-      (write-to-file part #:filename fname)
+      (write-to-file part #:path fname)
       (test-assert (access? fname R_OK))
       ;; note, the 23881 is the _encoded_ size.
       (test-equal 17674 (stat:size (stat fname))))
diff --git a/scm/mu-scm.scm b/scm/mu-scm.scm
index 197796ba..445921c6 100644
--- a/scm/mu-scm.scm
+++ b/scm/mu-scm.scm
@@ -28,6 +28,7 @@
 	    <mime-part>
 	    mime-part->alist
 	    make-port
+	    filename
 	    write-to-file
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 	    ;; Message
@@ -159,27 +160,33 @@ If DECODE? is #t, decode the content (from e.g., base64); in that case,
 CONTENT-ONLY? is implied to be #t."
   (cc-mime-make-stream-port (slot-ref mime-part 'mimepart) content-only? decode?))
 
-(define* (make-output-file mime-part #:key (filename #f) (overwrite? #f))
+(define-method (filename (mime-part <mime-part>))
+  "Determine the file-name for MIME-part.
+Either the 'filename' field in the mime-part and if that does not exist, use
+'mime-part-<index>' with <index> being the number of the mime-part."
+  (let ((alist (mime-part->alist mime-part)))
+    (or (assoc-ref  alist 'filename)
+	(format #f "mime-part-~d" (assoc-ref alist 'index)))))
+
+(define* (make-output-file mime-part #:key (path #f) (overwrite? #f))
   "Create a port for the file to write MIME-PART to.
 
-FILENAME is the path to the file name. If not specified, use the 'filename'
+PATH is file-name or path to the file name. If not specified, use the 'filename'
 field in the mime-part and if that does not exist, use 'mime-part-<index>' with
 <index> being the number of the mime-part.
 
 OVERWRITE? specifies whether existing files by the same name or overwritten.
 Otherwise, trying to overwrite an existing file raises an error."
   (let* ((alist (mime-part->alist mime-part))
-	(filename (or filename
-		      (assoc-ref alist 'filename)
-		      (format #f "mime-part-~d" (assoc-ref alist 'index)))))
-	;; we need an fd-based port since we want to support overwrite?
-	(open filename
-	      (logior O_WRONLY O_CREAT O_TRUNC (if overwrite? O_EXCL 0)) #o644)))
+	 (path (or path (filename mime-part))))
+    ;; we need an fd-based port since we want to support overwrite?
+    (open path
+	  (logior O_WRONLY O_CREAT O_TRUNC (if overwrite? O_EXCL 0)) #o644)))
 
-(define* (write-to-file mime-part #:key (filename #f) (overwrite? #f))
+(define* (write-to-file mime-part #:key (path #f) (overwrite? #f))
   "Write MIME-PART to a file.
 
-FILENAME is the path to the file name. If not specified, use the 'filename'
+PATH is the path/filename for the file. If not specified, use the 'filename'
 field in the mime-part and if that does not exist, use 'mime-part-<index>' with
 <index> being the number of the mime-part.
 
@@ -187,7 +194,7 @@ OVERWRITE? specifies whether existing files by the same name or overwritten.
 Otherwise, trying to overwrite an existing file raises an error."
   (let* ((input (make-port mime-part))
 	 (output (make-output-file mime-part
-				   #:filename filename #:overwrite? overwrite?))
+				   #:path path #:overwrite? overwrite?))
 	 (buf (make-bytevector 4096)) ;; just a guess...
 	 (bytes 0))
     (while (not (eof-object? bytes)) ;; XXX do this in a more elegant way.
diff --git a/scm/mu-scm.texi b/scm/mu-scm.texi
index 19bd0aae..517cf82c 100644
--- a/scm/mu-scm.texi
+++ b/scm/mu-scm.texi
@@ -515,12 +515,20 @@ case, @code{content-only?} is implied to be #t.
 Write MIME-part to file.
 
 Use @code{filename} is the file/path to use for writing; if this is @code{#f},
-the name is taken from the @t{filename} property of the MIME-part alist. If that
-does not exist, a generic name is chosen.
+the name using the @code{filename} procedure.
 
 If @code{overwrite?} is true, overwrite existing files of the same name;
 otherwise, raise an error if the file already exists.
 
+
+@deffn {Scheme Procedure} filename mime-part
+@end deffn
+Determine a filename for the given MIME-part.
+
+This is either taken from the @t{filename} property of the MIME-part alist, or,
+If that does not exist, a generic name.
+
+
 @subsection Contacts
 
 Message fields @t{To:}, @t{From:}, @t{Cc:} and @t{Bcc:} contain @emph{contacts}.