diff --git a/kittens/diff/config.py b/kittens/diff/config.py
index 17fefce35..053dfbcfd 100644
--- a/kittens/diff/config.py
+++ b/kittens/diff/config.py
@@ -3,7 +3,7 @@
 # License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
 
 import os
-from typing import Any, Dict, Iterable, Optional, Tuple, Type, Union
+from typing import Any, Dict, FrozenSet, Iterable, Optional, Tuple, Type, Union
 
 from kitty.cli_stub import DiffCLIOptions
 from kitty.conf.definition import config_lines
@@ -93,13 +93,16 @@ def special_handling(key: str, val: str, ans: Dict) -> bool:
 
 def parse_config(lines: Iterable[str], check_keys: bool = True) -> Dict[str, Any]:
     ans: Dict[str, Any] = {'key_definitions': {}}
+    defs: Optional[FrozenSet] = None
+    if check_keys:
+        defs = frozenset(defaults._fields)  # type: ignore
+
     parse_config_base(
         lines,
-        defaults,
+        defs,
         all_options,
         special_handling,
         ans,
-        check_keys=check_keys
     )
     return ans
 
diff --git a/kitty/conf/utils.py b/kitty/conf/utils.py
index 8263b62ab..f8fb2c48c 100644
--- a/kitty/conf/utils.py
+++ b/kitty/conf/utils.py
@@ -182,16 +182,14 @@ def _parse(
 
 def parse_config_base(
     lines: Iterable[str],
-    defaults: Any,
+    all_option_names: Optional[FrozenSet],
     all_options: Dict[str, Any],
     special_handling: Callable,
     ans: Dict[str, Any],
-    check_keys: bool = True,
     accumulate_bad_lines: Optional[List[BadLine]] = None
 ) -> None:
-    all_keys: Optional[FrozenSet[str]] = defaults._asdict() if check_keys else None
     _parse(
-        lines, create_type_converter(all_options), special_handling, ans, all_keys, accumulate_bad_lines
+        lines, create_type_converter(all_options), special_handling, ans, all_option_names, accumulate_bad_lines
     )
 
 
diff --git a/kitty/config.py b/kitty/config.py
index 7ec59ad67..0d1977f40 100644
--- a/kitty/config.py
+++ b/kitty/config.py
@@ -10,7 +10,7 @@ from contextlib import contextmanager, suppress
 from functools import partial
 from typing import (
     Any, Callable, Dict, Generator, Iterable, List, NamedTuple, Optional,
-    Sequence, Set, Tuple, Type, Union
+    Sequence, Set, Tuple, Type, Union, FrozenSet
 )
 
 from . import fast_data_types as defines
@@ -684,9 +684,9 @@ def parse_config(lines: Iterable[str], check_keys: bool = True, accumulate_bad_l
         'env': {}, 'kitten_aliases': {}, 'font_features': {}, 'mouse_mappings': [],
         'mousemap': {}
     }
-    defs: Optional[OptionsStub] = None
+    defs: Optional[FrozenSet] = None
     if check_keys:
-        defs = defaults
+        defs = frozenset(defaults._fields)  # type: ignore
 
     parse_config_base(
         lines,
@@ -694,7 +694,6 @@ def parse_config(lines: Iterable[str], check_keys: bool = True, accumulate_bad_l
         all_options,
         special_handling,
         ans,
-        check_keys=check_keys,
         accumulate_bad_lines=accumulate_bad_lines
     )
     return ans