diff --git a/synapse/_scripts/review_recent_signups.py b/synapse/_scripts/review_recent_signups.py
index e207f154f3aa..a935c50f426c 100644
--- a/synapse/_scripts/review_recent_signups.py
+++ b/synapse/_scripts/review_recent_signups.py
@@ -138,9 +138,7 @@ def main() -> None:
     config_args = parser.parse_args(sys.argv[1:])
     config_files = find_config_files(search_paths=config_args.config_path)
     config_dict = read_config_files(config_files)
-    config.parse_config_dict(
-        config_dict,
-    )
+    config.parse_config_dict(config_dict, "", "")
 
     since_ms = time.time() * 1000 - Config.parse_duration(config_args.since)
     exclude_users_with_email = config_args.exclude_emails
diff --git a/synapse/config/_base.py b/synapse/config/_base.py
index 8e19e2fc2668..179aa7ff887e 100644
--- a/synapse/config/_base.py
+++ b/synapse/config/_base.py
@@ -702,10 +702,7 @@ def load_or_generate_config(
         return obj
 
     def parse_config_dict(
-        self,
-        config_dict: Dict[str, Any],
-        config_dir_path: Optional[str] = None,
-        data_dir_path: Optional[str] = None,
+        self, config_dict: Dict[str, Any], config_dir_path: str, data_dir_path: str
     ) -> None:
         """Read the information from the config dict into this Config object.
 
diff --git a/synapse/config/_base.pyi b/synapse/config/_base.pyi
index 363d8b45545e..bd092f956dde 100644
--- a/synapse/config/_base.pyi
+++ b/synapse/config/_base.pyi
@@ -124,10 +124,7 @@ class RootConfig:
     @classmethod
     def invoke_all_static(cls, func_name: str, *args: Any, **kwargs: Any) -> None: ...
     def parse_config_dict(
-        self,
-        config_dict: Dict[str, Any],
-        config_dir_path: Optional[str] = ...,
-        data_dir_path: Optional[str] = ...,
+        self, config_dict: Dict[str, Any], config_dir_path: str, data_dir_path: str
     ) -> None: ...
     def generate_config(
         self,
diff --git a/synapse/config/key.py b/synapse/config/key.py
index 2f20575c3c52..ada65f6dd6e7 100644
--- a/synapse/config/key.py
+++ b/synapse/config/key.py
@@ -100,7 +100,7 @@ class KeyConfig(Config):
     section = "key"
 
     def read_config(
-        self, config: JsonDict, config_dir_path: Optional[str], **kwargs: Any
+        self, config: JsonDict, config_dir_path: str, **kwargs: Any
     ) -> None:
         # the signing key can be specified inline or in a separate file
         if "signing_key" in config:
diff --git a/tests/config/test_registration_config.py b/tests/config/test_registration_config.py
index 2acdb6ac6161..33d7b70e32ed 100644
--- a/tests/config/test_registration_config.py
+++ b/tests/config/test_registration_config.py
@@ -37,7 +37,9 @@ def test_session_lifetime_must_not_be_exceeded_by_smaller_lifetimes(self):
                     "session_lifetime": "30m",
                     "nonrefreshable_access_token_lifetime": "31m",
                     **config_dict,
-                }
+                },
+                "",
+                "",
             )
 
         with self.assertRaises(ConfigError):
@@ -46,7 +48,9 @@ def test_session_lifetime_must_not_be_exceeded_by_smaller_lifetimes(self):
                     "session_lifetime": "30m",
                     "refreshable_access_token_lifetime": "31m",
                     **config_dict,
-                }
+                },
+                "",
+                "",
             )
 
         with self.assertRaises(ConfigError):
@@ -55,7 +59,9 @@ def test_session_lifetime_must_not_be_exceeded_by_smaller_lifetimes(self):
                     "session_lifetime": "30m",
                     "refresh_token_lifetime": "31m",
                     **config_dict,
-                }
+                },
+                "",
+                "",
             )
 
         # Then test all the fine conditions
@@ -64,7 +70,9 @@ def test_session_lifetime_must_not_be_exceeded_by_smaller_lifetimes(self):
                 "session_lifetime": "31m",
                 "nonrefreshable_access_token_lifetime": "31m",
                 **config_dict,
-            }
+            },
+            "",
+            "",
         )
 
         HomeServerConfig().parse_config_dict(
@@ -72,11 +80,15 @@ def test_session_lifetime_must_not_be_exceeded_by_smaller_lifetimes(self):
                 "session_lifetime": "31m",
                 "refreshable_access_token_lifetime": "31m",
                 **config_dict,
-            }
+            },
+            "",
+            "",
         )
 
         HomeServerConfig().parse_config_dict(
-            {"session_lifetime": "31m", "refresh_token_lifetime": "31m", **config_dict}
+            {"session_lifetime": "31m", "refresh_token_lifetime": "31m", **config_dict},
+            "",
+            "",
         )
 
     def test_refuse_to_start_if_open_registration_and_no_verification(self):