diff --git a/kitty/boss.py b/kitty/boss.py
index d34017ded..3133d6870 100644
--- a/kitty/boss.py
+++ b/kitty/boss.py
@@ -1369,6 +1369,13 @@ class Boss:
                 return False
             if self.global_shortcuts_map and get_shortcut(self.global_shortcuts_map, ev):
                 return True
+            if not is_root_mode:
+                if mode.on_unknown in ('beep', 'ignore'):
+                    if mode.on_unknown == 'beep' and get_options().enable_audio_bell:
+                        ring_bell()
+                    return True
+                if mode.on_unknown == 'passthrough':
+                    return False
             if not self.pop_keyboard_mode():
                 if get_options().enable_audio_bell:
                     ring_bell()
@@ -1380,7 +1387,7 @@ class Boss:
                 if final_actions[0].is_sequence:
                     if not mode.is_sequence:
                         sm = KeyboardMode('__sequence__')
-                        sm.end_on_action = True
+                        sm.on_action = 'end'
                         sm.is_sequence = True
                         for fa in final_actions:
                             sm.keymap[fa.rest[0]].append(fa.shift_sequence_and_copy())
@@ -1399,7 +1406,7 @@ class Boss:
                     return True
                 final_action = final_actions[0]
                 consumed = self.combine(final_action.definition)
-                if consumed and not is_root_mode and mode.end_on_action:
+                if consumed and not is_root_mode and mode.on_action == 'end':
                     if mode_pos < len(self.keyboard_mode_stack) and self.keyboard_mode_stack[mode_pos] is mode:
                         del self.keyboard_mode_stack[mode_pos]
                         if not self.keyboard_mode_stack:
@@ -1463,7 +1470,7 @@ class Boss:
             self.current_visual_select.window_used_for_selection_id = 0 if w is None else w.id
             return
         km = KeyboardMode('__visual_select__')
-        km.end_on_action = True
+        km.on_action = 'end'
         fmap = get_name_to_functional_number_map()
         alphanumerics = get_options().visual_window_select_characters
         for idx, window in tab.windows.iter_windows_with_number(only_visible=True):
diff --git a/kitty/config.py b/kitty/config.py
index 324f9ffb6..67214175f 100644
--- a/kitty/config.py
+++ b/kitty/config.py
@@ -105,8 +105,8 @@ def finalize_keys(opts: Options, accumulate_bad_lines: Optional[List[BadLine]] =
     for defn in defns:
         if defn.options.new_mode:
             modes[defn.options.new_mode] = nm = KeyboardMode(defn.options.new_mode)
-            nm.passthrough_unknown = defn.options.passthrough_unknown
-            nm.end_on_action = defn.options.end_on_action
+            nm.on_unknown = defn.options.on_unknown
+            nm.on_action = defn.options.on_action
             defn.definition = f'push_keyboard_mode {defn.options.new_mode}'
         try:
             m = modes[defn.options.mode]
diff --git a/kitty/options/utils.py b/kitty/options/utils.py
index 87eeafbc0..a4c6da923 100644
--- a/kitty/options/utils.py
+++ b/kitty/options/utils.py
@@ -8,7 +8,25 @@ import sys
 from collections import defaultdict
 from dataclasses import dataclass, fields
 from functools import lru_cache
-from typing import Any, Callable, Container, Dict, FrozenSet, Iterable, Iterator, List, NamedTuple, Optional, Sequence, Tuple, Union
+from typing import (
+    Any,
+    Callable,
+    Container,
+    Dict,
+    FrozenSet,
+    Generic,
+    Iterable,
+    Iterator,
+    List,
+    Literal,
+    NamedTuple,
+    Optional,
+    Sequence,
+    Tuple,
+    TypeVar,
+    Union,
+    get_args,
+)
 
 import kitty.fast_data_types as defines
 from kitty.conf.utils import (
@@ -1134,20 +1152,29 @@ class MouseMapping(BaseDefinition):
         return MouseEvent(self.button, self.mods, self.repeat_count, self.grabbed)
 
 
-class BoolField:
-    def __init__(self, default: bool = False):
-        self._default = default
+T = TypeVar('T')
+
+
+class LiteralField(Generic[T]):
+    def __init__(self, vals: Tuple[T, ...]):
+        self._vals = vals
 
     def __set_name__(self, owner: object, name: str) -> None:
         self._name = "_" + name
 
-    def __get__(self, obj: object, type: Optional[type] = None) -> bool:
+    def __get__(self, obj: object, type: Optional[type] = None) -> T:
         if obj is None:
-            return self._default
-        return getattr(obj, self._name, self._default)
+            return self._vals[0]
+        return getattr(obj, self._name, self._vals[0])
 
     def __set__(self, obj: object, value: str) -> None:
-        setattr(obj, self._name, to_bool(value))
+        if value not in self._vals:
+            raise KeyError(f'Invalid value for {self._name[1:]}: {value!r}')
+        setattr(obj, self._name, value)
+
+
+OnUnknown = Literal['beep', 'end', 'ignore', 'passthrough']
+OnAction = Literal['keep', 'end']
 
 
 @dataclass(init=False, frozen=True)
@@ -1155,8 +1182,8 @@ class KeyMapOptions:
     when_focus_on: str = ''
     new_mode: str = ''
     mode: str = ''
-    passthrough_unknown: BoolField = BoolField(False)
-    end_on_action: BoolField = BoolField(False)
+    on_unknown = LiteralField[OnUnknown](get_args(OnUnknown))
+    on_action = LiteralField[OnAction](get_args(OnAction))
 
 
 default_key_map_options = KeyMapOptions()
@@ -1205,8 +1232,8 @@ class KeyDefinition(BaseDefinition):
 
 class KeyboardMode:
 
-    passthrough_unknown: bool = False
-    end_on_action: bool = False
+    on_unknown: OnUnknown = get_args(OnUnknown)[0]
+    on_action : OnAction = get_args(OnAction)[0]
     is_sequence: bool = False
 
     def __init__(self, name: str = '') -> None: