diff -up mozilla-release/config/baseconfig.mk.orig mozilla-release/config/baseconfig.mk
--- mozilla-release/config/baseconfig.mk.orig	2013-12-09 15:07:53.357724904 +0100
+++ mozilla-release/config/baseconfig.mk	2013-12-09 15:08:35.819797392 +0100
@@ -1,6 +1,6 @@
 includedir := $(includedir)/$(MOZ_APP_NAME)-$(MOZ_APP_VERSION)
 idldir = $(datadir)/idl/$(MOZ_APP_NAME)-$(MOZ_APP_VERSION)
-installdir = $(libdir)/$(MOZ_APP_NAME)-$(MOZ_APP_VERSION)
+installdir = $(libdir)/$(MOZ_APP_NAME)-last
 sdkdir = $(libdir)/$(MOZ_APP_NAME)-devel-$(MOZ_APP_VERSION)
 DIST = $(DEPTH)/dist
 
diff -up mozilla-release/js/src/config/baseconfig.mk.orig mozilla-release/js/src/config/baseconfig.mk
--- mozilla-release/js/src/config/baseconfig.mk.orig	2013-12-09 15:07:53.357724904 +0100
+++ mozilla-release/js/src/config/baseconfig.mk	2013-12-09 15:09:06.906850462 +0100
@@ -1,4 +1,4 @@
-installdir = $(libdir)/$(MOZ_APP_NAME)-$(MOZ_APP_VERSION)
+installdir = $(libdir)/$(MOZ_APP_NAME)-last
 sdkdir = $(libdir)/$(MOZ_APP_NAME)-devel-$(MOZ_APP_VERSION)
 
 ifneq (,$(filter /%,$(TOP_DIST)))