     when '-m', '--minify'
       opts.minify = true
     when '-o', '--output'
-      opts.output = args.shift()
+      opts.output.push args.shift()
     when '-p', '--prelude'
       opts.prelude = args.shift()
     when '--no-prelude'

  files:   []
  include: []
  minify:  false
  output:  null
  prelude: null
  strict:  false
  watch:   false

unless (opts.files.length or opts.preludeOnly)
  help()

if opts.watch and not opts.output.length
  error 'Output must be specified when using watch.'

# check that we have distinct outputs
if opts.files.length > 1 and (opts.output.indexOf '{}') == -1
  seen = {}
  for out in opts.output
    if seen[out]?
      error 'Output filenames overlap, perhaps you meant -o {}.js?'
    seen[out] = true

# If dedupe is chosen, prevent top level modules from being bundled into other
# top level modules.
