+set Version $(!builddate).$(vcsid)
+
+# Start by substituting the right version number in configure.ac.
+in puzzles do perl -i~ -pe 's/6.66/$(Version)/' configure.ac
+in puzzles do rm configure.ac~
+
+# And put it into the documentation as a versionid.
+# use perl to avoid inconsistent behaviour of echo '\v'
+in puzzles do perl -e 'print "\n\\versionid Simon Tatham'\''s Portable Puzzle Collection, version $$ARGV[0]\n"' $(Version) >> puzzles.but
+in puzzles do perl -e 'print "\n\\versionid Simon Tatham'\''s Portable Puzzle Collection, version $$ARGV[0]\n"' $(Version) >> devel.but
+
+# Write out a version.h that contains the real version number.
+in puzzles do echo '/* Generated by automated build script */' > version.h
+in puzzles do echo '$#define VER "Version $(Version)"' >> version.h
+
+# And do the same substitution in the OS X metadata. (This is a bit
+# icky in principle because it presumes that my version numbers don't
+# need XML escaping, but frankly, if they ever do then I should fix
+# them!)
+in puzzles do perl -i -pe 's/Unidentified build/$(Version)/' osx-info.plist
+