diff -Naur mozilla/config/autoconf.mk.in mozilla.tpg/config/autoconf.mk.in
--- mozilla/config/autoconf.mk.in	2008-05-05 21:08:14.000000000 +0000
+++ mozilla.tpg/config/autoconf.mk.in	2008-07-18 09:56:09.000000000 +0000
@@ -62,7 +62,7 @@
 libdir		= @libdir@
 datadir		= @datadir@
 mandir		= @mandir@
-idldir		= $(datadir)/idl/$(MOZ_APP_NAME)-$(MOZ_APP_VERSION)
+idldir		= $(includedir)
 
 installdir	= $(libdir)/$(MOZ_APP_NAME)-$(MOZ_APP_VERSION)
 sdkdir		= $(libdir)/$(MOZ_APP_NAME)-devel-$(MOZ_APP_VERSION)