diff --git a/archivebox/cli/tests.py b/archivebox/cli/tests.py
index 5e2e2d96..04c54df8 100644
--- a/archivebox/cli/tests.py
+++ b/archivebox/cli/tests.py
@@ -75,8 +75,8 @@ def output_hidden(show_failing=True):
         yield
         return
 
-    sys.stdout = open('stdout.txt', 'w+')
-    sys.stderr = open('stderr.txt', 'w+')
+    sys.stdout = open('stdout.txt', 'w+', encoding='utf-8')
+    sys.stderr = open('stderr.txt', 'w+', encoding='utf-8')
     try:
         yield
         sys.stdout.close()
@@ -89,9 +89,9 @@ def output_hidden(show_failing=True):
         sys.stdout = stdout
         sys.stderr = stderr
         if show_failing:
-            with open('stdout.txt', 'r') as f:
+            with open('stdout.txt', 'r', encoding='utf-8') as f:
                 print(f.read())
-            with open('stderr.txt', 'r') as f:
+            with open('stderr.txt', 'r', encoding='utf-8') as f:
                 print(f.read())
         raise
     finally:
@@ -116,7 +116,7 @@ class TestInit(unittest.TestCase):
         assert len(load_main_index(out_dir=OUTPUT_DIR)) == 0
 
     def test_conflicting_init(self):
-        with open(Path(OUTPUT_DIR) / 'test_conflict.txt', 'w+') as f:
+        with open(Path(OUTPUT_DIR) / 'test_conflict.txt', 'w+', encoding='utf-8') as f:
             f.write('test')
 
         try:
@@ -161,7 +161,7 @@ class TestAdd(unittest.TestCase):
 
     def test_add_arg_file(self):
         test_file = Path(OUTPUT_DIR) / 'test.txt'
-        with open(test_file, 'w+') as f:
+        with open(test_file, 'w+', encoding='utf') as f:
             f.write(test_urls)
 
         with output_hidden():
diff --git a/archivebox/config.py b/archivebox/config.py
index e9b30061..803e4d19 100644
--- a/archivebox/config.py
+++ b/archivebox/config.py
@@ -462,7 +462,7 @@ def write_config_file(config: Dict[str, str], out_dir: str=None) -> ConfigDict:
     config_file.optionxform = str
     config_file.read(config_path)
 
-    with open(config_path, 'r') as old:
+    with open(config_path, 'r', encoding='utf-8') as old:
         atomic_write(f'{config_path}.bak', old.read())
 
     find_section = lambda key: [name for name, opts in CONFIG_SCHEMA.items() if key in opts][0]
@@ -490,7 +490,7 @@ def write_config_file(config: Dict[str, str], out_dir: str=None) -> ConfigDict:
         else:
             config_file['SERVER_CONFIG'] = {'SECRET_KEY': random_secret_key}
 
-    with open(config_path, 'w+') as new:
+    with open(config_path, 'w+', encoding='utf-8') as new:
         config_file.write(new)
     
     try:
@@ -502,7 +502,7 @@ def write_config_file(config: Dict[str, str], out_dir: str=None) -> ConfigDict:
         }
     except:
         # something went horribly wrong, rever to the previous version
-        with open(f'{config_path}.bak', 'r') as old:
+        with open(f'{config_path}.bak', 'r', encoding='utf-8') as old:
             atomic_write(config_path, old.read())
 
     if Path(f'{config_path}.bak').exists():
@@ -1099,7 +1099,7 @@ def setup_django(out_dir: Path=None, check_db=False, config: ConfigDict=CONFIG,
         from django.conf import settings
 
         # log startup message to the error log
-        with open(settings.ERROR_LOG, "a+") as f:
+        with open(settings.ERROR_LOG, "a+", encoding='utf-8') as f:
             command = ' '.join(sys.argv)
             ts = datetime.now().strftime('%Y-%m-%d__%H:%M:%S')
             f.write(f"\n> {command}; ts={ts} version={config['VERSION']} docker={config['IN_DOCKER']} is_tty={config['IS_TTY']}\n")
diff --git a/archivebox/extractors/archive_org.py b/archivebox/extractors/archive_org.py
index 1f382190..a0883113 100644
--- a/archivebox/extractors/archive_org.py
+++ b/archivebox/extractors/archive_org.py
@@ -31,7 +31,7 @@ def should_save_archive_dot_org(link: Link, out_dir: Optional[Path]=None, overwr
 
     out_dir = out_dir or Path(link.link_dir)
     if not overwrite and (out_dir / 'archive.org.txt').exists():
-        # if open(path, 'r').read().strip() != 'None':
+        # if open(path, 'r', encoding='utf-8').read().strip() != 'None':
         return False
 
     return SAVE_ARCHIVE_DOT_ORG
diff --git a/archivebox/extractors/readability.py b/archivebox/extractors/readability.py
index b2e88712..d7c1e303 100644
--- a/archivebox/extractors/readability.py
+++ b/archivebox/extractors/readability.py
@@ -35,7 +35,7 @@ def get_html(link: Link, path: Path) -> str:
     document = None
     for source in sources:
         try:
-            with open(abs_path / source, "r") as f:
+            with open(abs_path / source, "r", encoding="utf-8") as f:
                 document = f.read()
                 break
         except (FileNotFoundError, TypeError):
diff --git a/archivebox/search/utils.py b/archivebox/search/utils.py
index e6d15455..82d1880e 100644
--- a/archivebox/search/utils.py
+++ b/archivebox/search/utils.py
@@ -16,7 +16,7 @@ def get_file_result_content(res, extra_path, use_pwd=False):
     if extra_path:
         fpath = f'{fpath}/{extra_path}'
 
-    with open(fpath, 'r') as file:
+    with open(fpath, 'r', encoding='utf-8') as file:
         data = file.read()
     if data:
         return [data]
diff --git a/archivebox/system.py b/archivebox/system.py
index 2191c70a..af0dbbb8 100644
--- a/archivebox/system.py
+++ b/archivebox/system.py
@@ -37,10 +37,11 @@ def atomic_write(path: Union[Path, str], contents: Union[dict, str, bytes], over
     """Safe atomic write to filesystem by writing to temp file + atomic rename"""
 
     mode = 'wb+' if isinstance(contents, bytes) else 'w'
+    encoding = None if isinstance(contents, bytes) else 'utf-8'
 
     # print('\n> Atomic Write:', mode, path, len(contents), f'overwrite={overwrite}')
     try:
-        with lib_atomic_write(path, mode=mode, overwrite=overwrite) as f:
+        with lib_atomic_write(path, mode=mode, overwrite=overwrite, encoding=encoding) as f:
             if isinstance(contents, dict):
                 dump(contents, f, indent=4, sort_keys=True, cls=ExtendedEncoder)
             elif isinstance(contents, (bytes, str)):
diff --git a/tests/test_add.py b/tests/test_add.py
index bb15e51b..331178fe 100644
--- a/tests/test_add.py
+++ b/tests/test_add.py
@@ -33,7 +33,7 @@ def test_depth_flag_0_crawls_only_the_arg_page(tmp_path, process, disable_extrac
     )
     
     archived_item_path = list(tmp_path.glob('archive/**/*'))[0]
-    with open(archived_item_path / "index.json", "r") as f:
+    with open(archived_item_path / "index.json", "r", encoding='utf-8') as f:
         output_json = json.load(f)
     assert output_json["base_url"] == "127.0.0.1:8080/static/example.com.html"
 
@@ -79,7 +79,7 @@ def test_add_updates_history_json_index(tmp_path, process, disable_extractors_di
 
     archived_item_path = list(tmp_path.glob('archive/**/*'))[0]
 
-    with open(archived_item_path / "index.json", "r") as f:
+    with open(archived_item_path / "index.json", "r", encoding="utf-8") as f:
         output_json = json.load(f)
     assert output_json["history"] != {}
 
@@ -90,4 +90,4 @@ def test_extract_input_uses_only_passed_extractors(tmp_path, process):
     archived_item_path = list(tmp_path.glob('archive/**/*'))[0]
 
     assert (archived_item_path / "warc").exists()
-    assert not (archived_item_path / "singlefile.html").exists()
\ No newline at end of file
+    assert not (archived_item_path / "singlefile.html").exists()
diff --git a/tests/test_extractors.py b/tests/test_extractors.py
index b467f0e1..86b50d51 100644
--- a/tests/test_extractors.py
+++ b/tests/test_extractors.py
@@ -86,7 +86,7 @@ def test_headers_retrieved(tmp_path, process, disable_extractors_dict):
     output_file = archived_item_path / "headers.json"
     assert output_file.exists()
     headers_file = archived_item_path / 'headers.json'
-    with open(headers_file) as f:
+    with open(headers_file, 'r', encoding='utf-8') as f:
         headers = pyjson.load(f)
     assert headers['Content-Language'] == 'en'
     assert headers['Content-Script-Type'] == 'text/javascript'
@@ -98,7 +98,7 @@ def test_headers_redirect_chain(tmp_path, process, disable_extractors_dict):
                                   capture_output=True, env=disable_extractors_dict)
     archived_item_path = list(tmp_path.glob("archive/**/*"))[0]
     output_file = archived_item_path / "headers.json" 
-    with open(output_file) as f:
+    with open(output_file, 'r', encoding='utf-8') as f:
         headers = pyjson.load(f)
     assert headers['Content-Language'] == 'en'
     assert headers['Content-Script-Type'] == 'text/javascript'
@@ -110,6 +110,6 @@ def test_headers_400_plus(tmp_path, process, disable_extractors_dict):
                                   capture_output=True, env=disable_extractors_dict)
     archived_item_path = list(tmp_path.glob("archive/**/*"))[0]
     output_file = archived_item_path / "headers.json" 
-    with open(output_file) as f:
+    with open(output_file, 'r', encoding='utf-8') as f:
         headers = pyjson.load(f)
-    assert headers["Status-Code"] == "200"
\ No newline at end of file
+    assert headers["Status-Code"] == "200"
diff --git a/tests/test_init.py b/tests/test_init.py
index 50897612..728aedfb 100644
--- a/tests/test_init.py
+++ b/tests/test_init.py
@@ -28,11 +28,11 @@ def test_add_link(tmp_path, process, disable_extractors_dict):
 
     assert "index.json" in [x.name for x in archived_item_path.iterdir()]
 
-    with open(archived_item_path / "index.json", "r") as f:
+    with open(archived_item_path / "index.json", "r", encoding="utf-8") as f:
         output_json = json.load(f)
     assert "Example Domain" == output_json['history']['title'][0]['output']
 
-    with open(archived_item_path / "index.html", "r") as f:
+    with open(archived_item_path / "index.html", "r", encoding="utf-8") as f:
         output_html = f.read()
     assert "Example Domain" in output_html
 
@@ -47,7 +47,7 @@ def test_add_link_support_stdin(tmp_path, process, disable_extractors_dict):
 
     assert "index.json" in [x.name for x in archived_item_path.iterdir()]
 
-    with open(archived_item_path / "index.json", "r") as f:
+    with open(archived_item_path / "index.json", "r", encoding="utf-8") as f:
         output_json = json.load(f)
     assert "Example Domain" == output_json['history']['title'][0]['output']
 
@@ -75,11 +75,11 @@ def test_collision_urls_different_timestamps(tmp_path, process, disable_extracto
     
     first_archive = tmp_path / "archive" / str(min([float(folder) for folder in archive_folders]))
     json_index = str(first_archive / "index.json")
-    with open(json_index, "r") as f:
+    with open(json_index, "r", encoding="utf-8") as f:
         link_details = json.loads(f.read())
 
     link_details["url"] = "http://127.0.0.1:8080/static/iana.org.html"
-    with open(json_index, "w") as f:
+    with open(json_index, "w", encoding="utf-8") as f:
         json.dump(link_details, f)
 
     init_process = subprocess.run(['archivebox', 'init'], capture_output=True, env=disable_extractors_dict)
@@ -98,12 +98,12 @@ def test_collision_timestamps_different_urls(tmp_path, process, disable_extracto
     archive_folders.remove(first_archive.name)
     json_index = str(first_archive / "index.json")
 
-    with open(json_index, "r") as f:
+    with open(json_index, "r", encoding="utf-8") as f:
         link_details = json.loads(f.read())
 
     link_details["timestamp"] = archive_folders[0]
 
-    with open(json_index, "w") as f:
+    with open(json_index, "w", encoding="utf-8") as f:
         json.dump(link_details, f)
 
     init_process = subprocess.run(['archivebox', 'init'], capture_output=True, env=disable_extractors_dict)