-prefix := @prefix@
-exec_prefix := @exec_prefix@
-bindir := @bindir@
-sbindir := @sbindir@
-libexecdir := @libexecdir@
-datadir := @datadir@
-sysconfdir := @datadir@
-sharedstatedir := @sharedstatedir@
-localstatedir := @localstatedir@
-libdir := @libdir@
-infodir := @infodir@
-includedir := @includedir@
-oldincludedir := @oldincludedir@
-mandir := @mandir@
-srcdir := @srcdir@
-
-#################################################################################
+prefix = @prefix@
+exec_prefix = @exec_prefix@
+bindir = @bindir@
+#UNUSED, see below: libexecdir = @libexecdir@
+datadir = @datadir@
+#sysconfdir = @datadir@
+#sharedstatedir = @sharedstatedir@
+#localstatedir = @localstatedir@
+libdir = @libdir@
+infodir = @infodir@
+includedir = @includedir@
+oldincludedir = @oldincludedir@
+mandir = @mandir@
+#UNUSED:srcdir = @srcdir@
+
+#
+# Default values for most of the above are only set if
+# they weren't configured to anything in particular
+# via the configure script. (i.e., we make no assumption
+# that the autoconf-generated script will assign defaults
+# to all of the above).
+#
+ifeq "$(strip $(exec_prefix))" ""
+exec_prefix = $(prefix)
+endif
+ifeq "$(strip $(bindir))" ""
+bindir = $(exec_prefix)/bin
+endif
+
+#
+# NOTE: by intention, libexecdir and libdir point to
+# the same place.
+# => Only way to override this is to set libexecdir= on the command line.
+# (NOTE: configure script setting is ignored).
+libexecdir = $(libdir)
+
+ifeq "$(strip $(datadir))" ""
+datadir = $(prefix)/share
+endif
+ifeq "$(strip $(libdir))" ""
+libdir = $(exec_prefix)/lib
+endif
+ifeq "$(strip $(infodir))" ""
+infodir = $(prefix)/info
+endif
+ifeq "$(strip $(includedir))" ""
+includedir = $(prefix)/include
+endif
+ifeq "$(strip $(oldincludedir))" ""
+oldincludedir = /usr/include
+endif
+ifeq "$(strip $(mandir))" ""
+mandir = $(prefix)/man
+endif
+
+
+################################################################################