addBuffer causes Error: write after end

[thejoshwolfe]

$ node test/zip.js --buffer index.js -o /dev/null 

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: write after end
    at writeAfterEnd (_stream_writable.js:132:12)
    at PassThrough.Writable.write (_stream_writable.js:180:5)
    at writeToOutputStream (/home/josh/dev/yazl/index.js:115:21)
    at /home/josh/dev/yazl/index.js:180:9
    at Array.forEach (native)
    at pumpEntries (/home/josh/dev/yazl/index.js:178:20)
    at Object._onImmediate (/home/josh/dev/yazl/index.js:84:9)
    at processImmediate [as _immediateCallback] (timers.js:345:15)