-atspi_datadir = join_paths(get_option('prefix'), get_option('datadir'))
-atspi_libexecdir = join_paths(get_option('prefix'), get_option('libexecdir'))
-atspi_sysconfdir = join_paths(get_option('prefix'), get_option('sysconfdir'))
+atspi_prefix = get_option('prefix')
+atspi_datadir = join_paths(atspi_prefix, get_option('datadir'))
+atspi_libexecdir = join_paths(atspi_prefix, get_option('libexecdir'))
+atspi_sysconfdir = join_paths(atspi_prefix, get_option('sysconfdir'))
+atspi_libdir = join_paths(atspi_prefix, get_option('libdir'))
+atspi_includedir = join_paths(atspi_prefix, get_option('includedir'))