diff --git a/shtab/__init__.py b/shtab/__init__.py
index 87ca026..b6f1ab6 100644
--- a/shtab/__init__.py
+++ b/shtab/__init__.py
@@ -211,8 +211,9 @@ def recurse(parser, prefix):
                                 new_nargs,
                             ) = recurse(
                                 positional.choices[choice],
-                                prefix + "_" + wordify(choice),
+                                f"{prefix}_{wordify(choice)}",
                             )
+
                             sub_subparsers.extend(new_subparsers)
                             sub_option_strings.extend(new_option_strings)
                             sub_compgens.extend(new_compgens)
@@ -421,10 +422,16 @@ def complete_bash(parser, root_prefix=None, preamble="", choice_functions=None):
     COMPREPLY=( $(compgen -W "${current_option_strings[*]}" -- "${completing_word}") )
   else
     # use choices & compgen
+    # call current_action_compgen without a subshell to support compopt
     local IFS=$'\\n'
+    tmpfile="$(mktemp)"
+    [ -n "${current_action_compgen}" ] && \\
+        "${current_action_compgen}" "${completing_word}" > "$tmpfile"
+    mapfile current_action_compreply < "$tmpfile"
+    rm "$tmpfile"
+
     COMPREPLY=( $(compgen -W "${current_action_choices}" -- "${completing_word}") \\
-                $([ -n "${current_action_compgen}" ] \\
-                  && "${current_action_compgen}" "${completing_word}") )
+        ${current_action_compreply[@]} )
   fi
 
   return 0
@@ -524,7 +531,7 @@ def recurse(parser, prefix, paths=None):
                         format_positional(opt) for opt in subparser._get_positional_actions()
                         if not isinstance(opt.choices, dict) if opt.help != SUPPRESS)
 
-                    new_pref = prefix + "_" + wordify(cmd)
+                    new_pref = f"{prefix}_{wordify(cmd)}"
                     options = all_commands[new_pref] = {
                         "cmd": cmd, "help": (subparser.description or "").strip().split("\n")[0],
                         "arguments": arguments, "paths": [*paths, cmd]}