Before I submit this to Ruby-bugs, am I doing something silly here:

     % cat t.rb
     MAGIC=159.chr
     "x".sub!(/#{MAGIC}(.)(.)/s, 'y')

     % ruby t.rb
     t.rb:2: unmatched ): /.)(.)/ (RegexpError)

     % ruby -v -e 'p $-K'
     ruby 1.6.2 (2001-01-18) [i686-linux]
     "NONE"

It happens whenever MAGIC has a value between 128 and 159.

Dave