-# We want to use the files shipped with Bison.
-BISON_SIMPLE='@top_srcpath@/src/bison.simple'
-export BISON_SIMPLE
-BISON_HAIRY='@top_srcpath@/src/bison.hairy'
-export BISON_HAIRY
-
-exec '@top_buildpath@/src/bison' ${1+"$@"}
+# Use the shipped files, not those installed.
+BISON_PKGDATADIR='@abs_top_srcdir@/data'
+export BISON_PKGDATADIR
+exec $PREBISON '@abs_top_builddir@/src/bison' ${1+"$@"}