diff --git a/bin/oxtimelines b/bin/oxtimelines
index 69c1701..a054953 100755
--- a/bin/oxtimelines
+++ b/bin/oxtimelines
@@ -42,7 +42,7 @@ tiles without having to decode the video again.
     parser.add_option('-s', '--sizes', dest='sizes', help='timeline size(s) (64 or 64,16)')
     parser.add_option('-w', '--wide', dest='wide', default=False, action='store_true', help='keep wide frames tiles')
     parser.add_option('-l', '--log', dest='log', default=False, action='store_true', help='log performance')
-    parser.add_option('-x', '--slit-position', dest='slit_position', default=None, action='store_true', help='slit scan position (default center frame)')
+    parser.add_option('-x', '--slit-position', dest='slit_position', default=None, help='slit scan position (default center frame)')
     (opts, args) = parser.parse_args()
 
     if None in (opts.modes, opts.sizes, opts.tiles) or not args:
@@ -55,4 +55,4 @@ tiles without having to decode the video again.
     opts.modes = [m.strip() for m in opts.modes.split(',')]
     opts.sizes = list(map(int, opts.sizes.split(',')))
 
-    oxtimelines.Timelines(opts.videos, opts.tiles, opts.cuts, opts.points, opts.modes, opts.sizes, opts.wide, opts.log, slit_positoin=opts.slit_position).render()
+    oxtimelines.Timelines(opts.videos, opts.tiles, opts.cuts, opts.points, opts.modes, opts.sizes, opts.wide, opts.log, slit_position=opts.slit_position).render()