diff --git a/src/mars_patcher/cli.py b/src/mars_patcher/cli.py
index 61b029a..7642918 100644
--- a/src/mars_patcher/cli.py
+++ b/src/mars_patcher/cli.py
@@ -1,9 +1,6 @@
 import argparse
-import copy
 import json
-import typing
 
-from mars_patcher.auto_generated_types import MarsSchema
 from mars_patcher.patcher import patch, validate_patch_data
 
 
@@ -18,11 +15,9 @@ def main() -> None:
     with open(args.patch_data_path, encoding="utf-8") as f:
         patch_data = json.load(f)
 
-    validate_patch_data(patch_data)
-
     patch(
         args.rom_path,
         args.out_path,
-        typing.cast(MarsSchema, copy.copy(patch_data)),
+        validate_patch_data(patch_data),
         lambda message, progress: print(message),
     )
diff --git a/src/mars_patcher/patcher.py b/src/mars_patcher/patcher.py
index a18b42f..31e389b 100644
--- a/src/mars_patcher/patcher.py
+++ b/src/mars_patcher/patcher.py
@@ -1,5 +1,7 @@
 import json
-from typing import Callable
+import typing
+from os import PathLike
+from typing import Callable, Union
 
 from jsonschema import validate
 
@@ -33,7 +35,7 @@
 from mars_patcher.text import write_seed_hash
 
 
-def validate_patch_data(patch_data: dict) -> None:
+def validate_patch_data(patch_data: dict) -> MarsSchema:
     """
     Validates whether the specified patch_data satisfies the schema for it.
 
@@ -43,11 +45,12 @@ def validate_patch_data(patch_data: dict) -> None:
     with open(get_data_path("schema.json")) as f:
         schema = json.load(f)
     validate(patch_data, schema)
+    return typing.cast(MarsSchema, patch_data)
 
 
 def patch(
-    input_path: str,
-    output_path: str,
+    input_path: Union[str, PathLike[str]],
+    output_path: Union[str, PathLike[str]],
     patch_data: MarsSchema,
     status_update: Callable[[str, float], None],
 ) -> None:
diff --git a/src/mars_patcher/rom.py b/src/mars_patcher/rom.py
index 69fc16f..f20ef60 100644
--- a/src/mars_patcher/rom.py
+++ b/src/mars_patcher/rom.py
@@ -82,7 +82,7 @@ class Rom:
         },
     }
 
-    def __init__(self, path: str):
+    def __init__(self, path: Union[str, PathLike[str]]):
         # Read file
         with open(path, "rb") as f:
             self.data = bytearray(f.read())