Segmentation Fault with :notes option

[logicaltext]

I'm getting a segmentation fault on Ruby 1.8.7-p174 when trying to use the :notes option multiple times in succession. This is happening in a Sinatra app (the first call works fine, but I get the segmentation fault when trying to refresh the page), but the issue can be replicated in IRB, and by running the following from the command line:

require 'rubygems'
require 'peg_markdown'
puts PEGMarkdown.new("Hello.[^1]\n\nSome more text.\n\n[^1]: A footnote.", :notes).to_html
puts PEGMarkdown.new("Hello.[^1]\n\nSome more text.\n\n[^1]: A footnote.", :notes).to_html

Any insight would be greatly appreciated.