diff --git a/UPDATING b/UPDATING
index 99ca688cff43..bdef007aaf9f 100644
--- a/UPDATING
+++ b/UPDATING
@@ -31,6 +31,22 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 11.x IS SLOW:
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20140606:
+	The libatf-c and libatf-c++ major versions were downgraded to 0 and
+	1 respectively to match the upstream numbers.  They were out of
+	sync because, when they were originally added to FreeBSD, the
+	upstream versions were not respected.  These libraries are private
+	and not yet built by default, so renumbering them should be a
+	non-issue.  However, unclean source trees will yield broken test
+	programs once the operator executes "make delete-old-libs" after a
+	"make installworld".
+
+	If you are using WITH_TESTS=yes (not the default), wipe the object
+	tree and rebuild from scratch to prevent spurious test failures.
+	This is only needed once: the old, misnumbered libraries have been
+	added to OptionalObsoleteFiles.inc so they will be removed during a
+	clean upgrade.
+
 20140512:
 	Clang and llvm have been upgraded to 3.4.1 release.
 
diff --git a/lib/atf/libatf-c++/Makefile b/lib/atf/libatf-c++/Makefile
index 121b77d486f7..163f7fbf363b 100644
--- a/lib/atf/libatf-c++/Makefile
+++ b/lib/atf/libatf-c++/Makefile
@@ -30,7 +30,7 @@
 
 LIB=		atf-c++
 PRIVATELIB=	true
-SHLIB_MAJOR=	2
+SHLIB_MAJOR=	1
 
 # libatf-c++ depends on the C version of the ATF library to build.
 DPADD=		${LIBATFC}
diff --git a/lib/atf/libatf-c/Makefile b/lib/atf/libatf-c/Makefile
index f067ede853fc..4920eb5c78cd 100644
--- a/lib/atf/libatf-c/Makefile
+++ b/lib/atf/libatf-c/Makefile
@@ -30,7 +30,7 @@
 
 LIB=		atf-c
 PRIVATELIB=	true
-SHLIB_MAJOR=	1
+SHLIB_MAJOR=	0
 
 ATF=		${.CURDIR:H:H:H}/contrib/atf
 .PATH:		${ATF}
diff --git a/tools/build/mk/OptionalObsoleteFiles.inc b/tools/build/mk/OptionalObsoleteFiles.inc
index 6645be6ed522..bd062b3a60c0 100644
--- a/tools/build/mk/OptionalObsoleteFiles.inc
+++ b/tools/build/mk/OptionalObsoleteFiles.inc
@@ -4112,6 +4112,8 @@ OLD_LIBS+=usr/lib/libatf-c.a
 OLD_LIBS+=usr/lib/libatf-c.so
 OLD_LIBS+=usr/lib/libatf-c.so.1
 OLD_LIBS+=usr/lib/libatf-c_p.a
+OLD_LIBS+=usr/lib/private/libatf-c.so.1
+OLD_LIBS+=usr/lib/private/libatf-c++.so.2
 .if ${TARGET_ARCH} == "amd64" || ${TARGET_ARCH} == "powerpc64"
 OLD_LIBS+=usr/lib32/libatf-c++.a
 OLD_LIBS+=usr/lib32/libatf-c++.so
@@ -4122,6 +4124,8 @@ OLD_LIBS+=usr/lib32/libatf-c.a
 OLD_LIBS+=usr/lib32/libatf-c.so
 OLD_LIBS+=usr/lib32/libatf-c.so.1
 OLD_LIBS+=usr/lib32/libatf-c_p.a
+OLD_LIBS+=usr/lib32/private/libatf-c.so.1
+OLD_LIBS+=usr/lib32/private/libatf-c++.so.2
 .endif
 OLD_FILES+=usr/libdata/pkgconfig/atf-c++.pc
 OLD_FILES+=usr/libdata/pkgconfig/atf-c.pc