fix wrong command line argument check
diff --git a/pyserial/examples/miniterm.py b/pyserial/examples/miniterm.py
index a85f1d8..895830c 100644
--- a/pyserial/examples/miniterm.py
+++ b/pyserial/examples/miniterm.py
@@ -480,7 +480,7 @@
     if options.cr and options.lf:
         parser.error("only one of --cr or --lf can be specified")
 
-    if options.dtr_state is not None and options.rts_state is not None and options.dtr_state == options.rts_state:
+    if options.menu_char == options.exit_char:
         parser.error('--exit-char can not be the same as --menu-char')
 
     global EXITCHARCTER, MENUCHARACTER