--- a/impressive.py
+++ b/impressive.py
@@ -6242,7 +6242,7 @@ def ParseOptions(argv):
             "noback", "pages=", "poll=", "font=", "fontsize=", "gamma=",
             "duration=", "cursor=", "minutes", "layout=", "script=", "cache=",
             "cachefile=", "autooverview=", "zoomtime=", "fade", "nologo",
-            "shuffle", "page-progress", "overscan", "autoquit", "noclicks",
+            "shuffle", "page-progress", "overscan=", "autoquit", "noclicks",
             "clock", "half-screen", "spot-radius=", "invert", "min-box-size=",
             "auto-auto", "auto-progress", "darkness=", "no-clicks", "nowheel",
             "no-wheel", "fake-fullscreen", "windowed", "verbose", "noblur",
