diff --git a/pyencrypt/encrypt.py b/pyencrypt/encrypt.py
index 9d4dc28..48c6f7d 100644
--- a/pyencrypt/encrypt.py
+++ b/pyencrypt/encrypt.py
@@ -57,13 +57,14 @@ def generate_so_file(cipher_key: str, d: int, n: int, base_dir: Optional[Path] =
     need_import_files = ['ntt.py', 'aes.py', 'decrypt.py', 'license.py']
     for file in need_import_files:
         file_path = path / file
-        decrypt_source_ls.append(REMOVE_SELF_IMPORT.sub('', file_path.read_text()))
+        decrypt_source_ls.append(REMOVE_SELF_IMPORT.sub('', file_path.read_text(encoding="utf-8")))
 
     loader_source_path = path / 'loader.py'
-    loader_source = REMOVE_SELF_IMPORT.sub('', loader_source_path.read_text()).replace(
-        "__private_key = ''", f"__private_key = '{private_key}'", 1
-    ).replace("__cipher_key = ''", f"__cipher_key = '{cipher_key}'", 1).replace(
-        'license = None', f'license = {license}', 1
+    loader_source = (
+        REMOVE_SELF_IMPORT.sub("", loader_source_path.read_text(encoding="utf-8"))
+        .replace("__private_key = ''", f"__private_key = '{private_key}'", 1)
+        .replace("__cipher_key = ''", f"__cipher_key = '{cipher_key}'", 1)
+        .replace("license = None", f"license = {license}", 1)
     )
 
     if base_dir is None:
@@ -79,9 +80,14 @@ def generate_so_file(cipher_key: str, d: int, n: int, base_dir: Optional[Path] =
     # Origin file
     loader_origin_file_path = temp_dir / 'loader_origin.py'
     loader_origin_file_path.touch(exist_ok=True)
-    loader_origin_file_path.write_text(f"{decrypt_source}\n{loader_source}")
+    loader_origin_file_path.write_text(
+        f"{decrypt_source}\n{loader_source}", encoding="utf-8"
+    )
 
-    loader_file_path.write_text(python_minifier.minify(loader_origin_file_path.read_text()))
+    loader_file_path.write_text(
+        python_minifier.minify(loader_origin_file_path.read_text(encoding="utf-8")),
+        encoding="utf-8",
+    )
 
     from setuptools import setup  # isort:skip
     from Cython.Build import cythonize
diff --git a/tests/conftest.py b/tests/conftest.py
index 6f15770..87ff186 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -30,7 +30,7 @@ def file_and_loader(request, tmp_path_factory):
     file_path.write_text("""\
 def {function_name}():
 {code}
-    """.format(function_name=function_name, code=code))
+    """.format(function_name=function_name, code=code), encoding='utf-8')
     # generate loader.so
     key = generate_aes_key()
     new_path = file_path.with_suffix('.pye')
@@ -74,7 +74,7 @@ def package_and_loader(request, tmp_path_factory):
     file_path.write_text("""\
 def {function_name}():
 {code}
-    """.format(function_name=function_name, code=code))
+    """.format(function_name=function_name, code=code), encoding='utf-8')
 
     new_path = file_path.with_suffix('.pye')
     key = generate_aes_key()
diff --git a/tests/test_license.py b/tests/test_license.py
index 2ecd133..df5db90 100644
--- a/tests/test_license.py
+++ b/tests/test_license.py
@@ -81,7 +81,7 @@ def test_check_license_invalid(self, key, tmp_path):
         license_file_path = generate_license_file(key, path=tmp_path)
         license_data = json.loads(license_file_path.read_text())
         license_data['signature'] = 'invalid'
-        license_file_path.write_text(json.dumps(license_data))
+        license_file_path.write_text(json.dumps(license_data), encoding='utf-8')
         with pytest.raises(Exception) as excinfo:
             check_license(license_file_path, key)
         assert str(excinfo.value) == 'License signature is invalid.'