diff --git a/Makefile.inc1 b/Makefile.inc1
index 7c50b4ce256a..0c5cdb78aefc 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -1,5 +1,5 @@
 #
-#	$Id: Makefile.inc1,v 1.55 1999/01/04 12:05:59 bde Exp $
+#	$Id: Makefile.inc1,v 1.56 1999/01/06 10:06:36 bde Exp $
 #
 # Make command line options:
 #	-DCLOBBER will remove /usr/include
@@ -945,6 +945,16 @@ check-objformat	:
 	@/bin/sh -c "echo \"in your environment.\" "
 	@exit 1
 .endif
+.if	!defined(REALLY_WANT_DEPRECIATED_AOUT) && ${OBJFORMAT} == "aout"
+	@echo "==== NOTICE: a.out buildworld is depreciated and disabled! ====="
+	@echo "Read: http://www.freebsd.org/~peter/elfday.html for information."
+	@echo "You need to complete a 'make aout-to-elf' to bring your system"
+	@echo "up to date with ELF tools.  This requires a fair amount of disk"
+	@echo "space to complete.  Alternatively, you can do a binary upgrade"
+	@echo "using the 3.0-RELEASE binaries from CD or ftp.freebsd.org in"
+	@echo "/pub/FreeBSD/3.0-RELEASE/bin/ to convert your userland to ELF."
+	@exit 1
+.endif
 
 
 .for __target in clean cleandepend cleandir depend obj