diff --git a/bin/sigal b/bin/sigal
index db06692..6f48f0b 100755
--- a/bin/sigal
+++ b/bin/sigal
@@ -35,7 +35,7 @@ __license__ = "GPL"
 
 import os
 import sys
-from optparse import OptionParser
+import argparse
 from sigal.image import Gallery
 from sigal.params import read_params
 from sigal.theme import Theme
@@ -43,41 +43,35 @@ from sigal.theme import Theme
 def main():
     "main program"
 
-    # command line options
-    usage = "usage: %prog [options] inputdir outputdir"
     version = "version %s, %s" % (__version__, __date__)
 
-    parser = OptionParser(usage=usage, version="%prog "+version)
+    parser = argparse.ArgumentParser(description='simple static gallery generator.')
+    parser.add_argument('input_dir', help='input directory')
+    parser.add_argument('output_dir', help='output directory')
+    parser.add_argument('--version', action='version',
+                        version="%(prog)s " + version)
+    parser.add_argument('-c', '--copyright',
+                        help="copyright message added to the images")
+    parser.add_argument("-f", "--force", action='store_true',
+                        help="force the reprocessing of existing images and thumbnails")
 
-    parser.add_option("-c", "--copyright", dest="copyright",
-                      help="copyright message added to the images")
-    parser.add_option("-f", "--force", dest="force",
-                      help="force the reprocessing of existing images and thumbnails")
+    args = parser.parse_args()
 
-    (options, args) = parser.parse_args()
-
-    if len(args) != 2:
-        parser.print_help()
-        sys.exit()
-
-    input_dir = args[0]
-    output_dir = args[1]
-
-    if not os.path.isdir(input_dir):
-        print "Directory %s does not exist." % input_dir
+    if not os.path.isdir(args.input_dir):
+        print "Directory %s does not exist." % args.input_dir
         sys.exit(1)
 
     print ":: Reading parameters ..."
-    params = read_params(input_dir)
+    params = read_params(args.input_dir)
 
-    if options.copyright:
-        params.set('sigal', 'copyright', options.copyright)
+    if args.copyright:
+        params.set('sigal', 'copyright', args.copyright)
 
     # create gallery
     gallery = Gallery(params)
-    gallery.build(input_dir, output_dir, force=options.force)
+    gallery.build(args.input_dir, args.output_dir, force=args.force)
 
-    r = Theme(params, output_dir)
+    r = Theme(params, args.output_dir)
     r.render()
 
     return 0