diff --git a/ms/INSTALL b/ms/INSTALL
index 5ee35b7..8e926a1 100644
--- a/ms/INSTALL
+++ b/ms/INSTALL
@@ -1,13 +1,20 @@
 This directory is for building GNU diffutils on PC operating systems.
-It currently assumes GCC and emx.
+It currently assumes GCC with either DJGPP or emx.
 
-To build, check `Makefile' (particularly its configuration section)
-and then do the following:
+To build, check `pc/LIB/Makefile' (particularly its definitions for
+`prefix' and `exec_prefix') and then do the following:
 
 	cd ..
-	make -f pc/Makefile OS-TARGET
+	make -f pc/LIB/Makefile OS-TARGET
 
-where OS is either `dos' or `os2', and TARGET is either `debug' or `release'.
+where
 
-If you change pc/Makefile, check your changes by running
-`make -f pc/Makefile pc/Makefile.chk'.
+	LIB is either `djgpp' or `emx'.
+	OS is either `dos' or `os2'.
+	TARGET is either `debug' or `release'.
+
+If you change pc/djgpp/Makefile, check your changes by running
+`make -f pc/Makefile.add check-makefile ENV=djgpp'; likewise for emx.
+
+The makefiles have the minimal changes from `../Makefile'
+and may therefore contain targets that may not apply on your hosts.