+docdir := $(docdir)/libraries/$$pkgid
+ifeq "$(Windows)" "YES"
+# On Windows we want to make moveable bindists, but we need to tell
+# ghc-pkg where the haddock docs are. Therefore we completely ignore
+# where the user tells us to put the haddock documentation and put it
+# somewhere whose relative location we know. When installing we need
+# to give Cabal a real path, though.
+htmldir_configure = $$topdir/doc/libraries/$$pkgid
+htmldir_install = $(prefix)/doc/libraries/$$pkgid
+else
+# On non-Windows we can just give absolute paths all the time, and
+# thus obey the htmldir that we are given.
+htmldir_configure = $(htmldir)/libraries/$$pkgid
+htmldir_install = $(htmldir_configure)
+endif
+