diff --git a/UPDATING b/UPDATING
index 871176a70be3..bb8ddc6c04e5 100644
--- a/UPDATING
+++ b/UPDATING
@@ -714,11 +714,13 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 13.x IS SLOW:
 	system will be running the ino64 kernel with the existing world).
 
 	For the safest in-place upgrade begin by removing previous build
-	artifacts via "rm -rf /usr/obj/*".   Then, carefully follow the
-	full procedure documented below under the heading "To rebuild
-	everything and install it on the current system."  Specifically,
-	a reboot is required after installing the new kernel before
-	installing world.
+	artifacts via "rm -rf /usr/obj/*".  Then, carefully follow the full
+	procedure documented below under the heading "To rebuild everything and
+	install it on the current system."  Specifically, a reboot is required
+	after installing the new kernel before installing world. While an
+	installworld normally works by accident from multiuser after rebooting
+	the proper kernel, there are many cases where this will fail across this
+	upgrade and installworld from single user is required.
 
 20170424:
 	The NATM framework including the en(4), fatm(4), hatm(4), and