diff -up firefox-45.0/firefox-45.0/config/baseconfig.mk.orig firefox-45.0/firefox-45.0/config/baseconfig.mk
--- firefox-45.0/config/baseconfig.mk.orig	2016-03-02 13:26:31.981927073 +0100
+++ firefox-45.0/config/baseconfig.mk	2016-03-02 13:30:09.044756473 +0100
@@ -4,7 +4,7 @@
 # whether a normal build is happening or whether the check is running.
 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)
 sdkdir = $(libdir)/$(MOZ_APP_NAME)-devel-$(MOZ_APP_VERSION)
 ifeq (.,$(DEPTH))
 DIST = dist