diff --git a/src/textual/app.py b/src/textual/app.py
index 9139dd514..4c8762508 100644
--- a/src/textual/app.py
+++ b/src/textual/app.py
@@ -107,6 +107,7 @@ from textual.keys import (
     REPLACED_KEYS,
     _character_to_key,
     _get_unicode_name_from_key,
+    _normalize_key_list,
     format_key,
 )
 from textual.messages import CallbackType, Prune
@@ -3709,7 +3710,10 @@ class App(Generic[ReturnType], DOMNode):
         Args:
             keymap: A mapping of binding IDs to key strings.
         """
-        self._keymap = keymap
+
+        self._keymap = {
+            binding_id: _normalize_key_list(keys) for binding_id, keys in keymap.items()
+        }
         self.refresh_bindings()
 
     def update_keymap(self, keymap: Keymap) -> None:
@@ -3721,6 +3725,9 @@ class App(Generic[ReturnType], DOMNode):
         Args:
             keymap: A mapping of binding IDs to key strings.
         """
+        keymap = {
+            binding_id: _normalize_key_list(keys) for binding_id, keys in keymap.items()
+        }
         self._keymap = {**self._keymap, **keymap}
         self.refresh_bindings()
 
diff --git a/src/textual/keys.py b/src/textual/keys.py
index b4eb6236d..c34e9edf7 100644
--- a/src/textual/keys.py
+++ b/src/textual/keys.py
@@ -354,3 +354,16 @@ def _character_to_key(character: str) -> str:
         key = character
     key = KEY_NAME_REPLACEMENTS.get(key, key)
     return key
+
+
+def _normalize_key_list(keys: str) -> str:
+    """Normalizes a comma separated list of keys.
+
+    Replaces single letter keys with full name.
+    Sorts alphabetically.
+    """
+
+    keys_list = [key.strip() for key in keys.split(",")]
+    return ",".join(
+        _character_to_key(key) if len(key) == 1 else key for key in sorted(keys_list)
+    )
diff --git a/tests/test_binding.py b/tests/test_binding.py
index 2aaf500a1..d11158f9f 100644
--- a/tests/test_binding.py
+++ b/tests/test_binding.py
@@ -127,3 +127,13 @@ async def test_keymap_update() -> None:
         app.set_keymap({"quit": "f1"})
         await pilot.pause()
         assert bindings_updated == [app.screen, app.screen]
+
+
+async def test_keymap_key() -> None:
+    app: App[None] = App()
+
+    async with app.run_test():
+        app.set_keymap({"foo": "?,space"})
+        assert app._keymap == {"foo": "question_mark,space"}
+        app.update_keymap({"bar": "$"})
+        assert app._keymap == {"bar": "dollar_sign", "foo": "question_mark,space"}