diff --git a/src/openjd/adaptor_runtime/_entrypoint.py b/src/openjd/adaptor_runtime/_entrypoint.py
index 23ad98d..1365b25 100644
--- a/src/openjd/adaptor_runtime/_entrypoint.py
+++ b/src/openjd/adaptor_runtime/_entrypoint.py
@@ -590,14 +590,14 @@ def _load_data(data: str) -> dict:
 
 def _load_yaml_json(data: str) -> Any:
     """
-    Loads a YAML/JSON file/string.
+    Loads a YAML/JSON file/string using the UTF-8 encoding.
 
     Note that yaml.safe_load() is capable of loading JSON documents.
     """
     loaded_yaml = None
     if data.startswith("file://"):
         filepath = data[len("file://") :]
-        with open(filepath) as yaml_file:
+        with open(filepath, encoding="utf-8") as yaml_file:
             loaded_yaml = yaml.safe_load(yaml_file)
     else:
         loaded_yaml = yaml.safe_load(data)
diff --git a/test/openjd/adaptor_runtime/unit/test_entrypoint.py b/test/openjd/adaptor_runtime/unit/test_entrypoint.py
index 46adc5d..50e58ac 100644
--- a/test/openjd/adaptor_runtime/unit/test_entrypoint.py
+++ b/test/openjd/adaptor_runtime/unit/test_entrypoint.py
@@ -860,12 +860,12 @@ def test_accepts_file(self, input: str, expected: dict):
 
         # WHEN
         open_mock: MagicMock
-        with patch.object(runtime_entrypoint, "open", mock_open(read_data=input)) as open_mock:
+        with patch.object(runtime_entrypoint, "open", mock_open(read_data=input), "encoding=utf8") as open_mock:
             output = _load_data(file_uri)
 
         # THEN
         assert output == expected
-        open_mock.assert_called_once_with(filepath)
+        open_mock.assert_called_once_with(filepath, encoding="utf-8")
 
     @patch.object(runtime_entrypoint, "open")
     def test_raises_on_os_error(self, mock_open: MagicMock, caplog: pytest.LogCaptureFixture):
@@ -880,7 +880,7 @@ def test_raises_on_os_error(self, mock_open: MagicMock, caplog: pytest.LogCaptur
 
         # THEN
         assert raised_err.value is mock_open.side_effect
-        mock_open.assert_called_once_with(filepath)
+        mock_open.assert_called_once_with(filepath, encoding="utf-8")
         assert "Failed to open data file: " in caplog.text
 
     def test_raises_when_parsing_fails(self, caplog: pytest.LogCaptureFixture):