diff --git a/utils/modular_model_converter.py b/utils/modular_model_converter.py
index c107a4831862..bda143c25772 100644
--- a/utils/modular_model_converter.py
+++ b/utils/modular_model_converter.py
@@ -56,7 +56,7 @@ def get_module_source_from_name(module_name: str) -> str:
     if spec is None or spec.origin is None:
         return f"Module {module_name} not found"
 
-    with open(spec.origin, "r") as file:
+    with open(spec.origin, "r", encoding="utf-8") as file:
         source_code = file.read()
     return source_code
 
@@ -1132,7 +1132,7 @@ def convert_modular_file(modular_file, old_model_name=None, new_model_name=None,
     if pattern is not None:
         model_name = pattern.groups()[0]
         # Parse the Python file
-        with open(modular_file, "r") as file:
+        with open(modular_file, "r", encoding="utf-8") as file:
             code = file.read()
         module = cst.parse_module(code)
         wrapper = MetadataWrapper(module)
@@ -1143,7 +1143,7 @@ def convert_modular_file(modular_file, old_model_name=None, new_model_name=None,
             if node != {}:
                 # Get relative path starting from src/transformers/
                 relative_path = re.search(
-                    rf"(src{os.sep}transformers{os.sep}.*|examples{os.sep}.*)", os.path.abspath(modular_file)
+                    r"(src/transformers/.*|examples/.*)", os.path.abspath(modular_file).replace("\\", "/")
                 ).group(1)
 
                 header = AUTO_GENERATED_MESSAGE.format(
@@ -1164,7 +1164,7 @@ def save_modeling_file(modular_file, converted_file):
             [line for line in converted_file[file_type][0].strip().split("\n") if not line.strip().startswith("#")]
         )
         if len(converted_file[file_type][0].strip()) > 0 and non_comment_lines > 0:
-            with open(modular_file.replace("modular_", f"{file_type}_"), "w") as f:
+            with open(modular_file.replace("modular_", f"{file_type}_"), "w", encoding="utf-8") as f:
                 f.write(converted_file[file_type][0])
         else:
             non_comment_lines = len(
@@ -1172,7 +1172,7 @@ def save_modeling_file(modular_file, converted_file):
             )
             if len(converted_file[file_type][1].strip()) > 0 and non_comment_lines > 0:
                 logger.warning("The modeling code contains errors, it's written without formatting")
-                with open(modular_file.replace("modular_", f"{file_type}_"), "w") as f:
+                with open(modular_file.replace("modular_", f"{file_type}_"), "w", encoding="utf-8") as f:
                     f.write(converted_file[file_type][1])