diff --git a/examples/customcomplete.py b/examples/customcomplete.py
index 89e2285..1646845 100755
--- a/examples/customcomplete.py
+++ b/examples/customcomplete.py
@@ -23,8 +23,9 @@
 
 
 def process(args):
-    print("received <input_txt>=%r --input-file=%r --output-name=%r" %
-          (args.input_txt, args.input_file, args.output_name))
+    print(
+        "received <input_txt>=%r [<suffix>=%r] --input-file=%r --output-name=%r --hidden-opt=%r" %
+        (args.input_txt, args.suffix, args.input_file, args.output_name, args.hidden_opt))
 
 
 def get_main_parser():
@@ -39,7 +40,7 @@ def get_main_parser():
 
     parser = subparsers.add_parser("process", help="parse files")
     # `*.txt` file tab completion
-    parser.add_argument("input_txt", nargs="?").complete = TXT_FILE
+    parser.add_argument("input_txt", nargs='?').complete = TXT_FILE
     # file tab completion builtin shortcut
     parser.add_argument("-i", "--input-file").complete = shtab.FILE
     parser.add_argument(
@@ -50,8 +51,9 @@ def get_main_parser():
     ).complete = shtab.DIRECTORY
     # directory tab completion builtin shortcut
 
-    main_parser.add_argument('suffix', choices=['json', 'csv'], default='json',
-                             help="Output format")
+    parser.add_argument("suffix", choices=['json', 'csv'], default='json', nargs='?',
+                        help="Output format")
+    parser.add_argument("--hidden-opt", action='store_true', help=argparse.SUPPRESS)
     parser.set_defaults(func=process)
     return main_parser
 
diff --git a/shtab/__init__.py b/shtab/__init__.py
index 7a7240e..d63952c 100644
--- a/shtab/__init__.py
+++ b/shtab/__init__.py
@@ -624,14 +624,15 @@ def recurse_parser(cparser, positional_idx, requirements=None):
 
         for optional in cparser._get_optional_actions():
             log.debug('%s| Optional: %s', log_prefix, optional.dest)
-            # Mingle all optional arguments for all subparsers
-            for optional_str in optional.option_strings:
-                log.debug('%s| | %s', log_prefix, optional_str)
-                if optional_str.startswith('--'):
-                    optionals_double.add(optional_str[2:])
-                elif optional_str.startswith('-'):
-                    optionals_single.add(optional_str[1:])
-                specials.extend(get_specials(optional, 'n', optional_str))
+            if optional.help != SUPPRESS:
+                # Mingle all optional arguments for all subparsers
+                for optional_str in optional.option_strings:
+                    log.debug('%s| | %s', log_prefix, optional_str)
+                    if optional_str.startswith('--'):
+                        optionals_double.add(optional_str[2:])
+                    elif optional_str.startswith('-'):
+                        optionals_single.add(optional_str[1:])
+                    specials.extend(get_specials(optional, 'n', optional_str))
 
         for positional in cparser._get_positional_actions():
             if positional.help != SUPPRESS: