diff --git a/pcl/simple-streams/external-formats/aliases b/pcl/simple-streams/external-formats/aliases
index e24d39a7ac6d7e0da6b4f1297551e9c478b309d3..1897a5d4c0ff32bb168a0dbb05bce99a0a62a479 100644
--- a/pcl/simple-streams/external-formats/aliases
+++ b/pcl/simple-streams/external-formats/aliases
@@ -99,3 +99,7 @@ windows-latin1	cp1252
 ;; characters to Lisp #\newline character.  On output, #\newline is
 ;; converted to CR LF sequence.
 dos		crlf
+
+;; A composing format for converting MAC end-of-line (CR) character to
+;; Lisp #\newline character
+mac		cr