diff --git a/tests/test_cmark_spec/get_cmark_spec.py b/tests/test_cmark_spec/get_cmark_spec.py
index 2883835e..2ced0285 100644
--- a/tests/test_cmark_spec/get_cmark_spec.py
+++ b/tests/test_cmark_spec/get_cmark_spec.py
@@ -72,9 +72,12 @@ def _json_to_fixture(data: list[dict[str, Any]]) -> str:
         print(f"Downloading CommonMark spec from {url}")
         response = requests.get(url)
         response.raise_for_status()
-        if not output_path.exists() or output_path.read_text() != response.text:
+        if (
+            not output_path.exists()
+            or output_path.read_text(encoding="utf-8") != response.text
+        ):
             changed = True
-            with output_path.open("w") as f:
+            with output_path.open("w", encoding="utf-8") as f:
                 f.write(response.text)
             print(f"Updated to {output_path}")
         else:
@@ -85,9 +88,9 @@ def _json_to_fixture(data: list[dict[str, Any]]) -> str:
     response.raise_for_status()
     data = response.json()
     text = _json_to_fixture(data)
-    if not test_fixture.exists() or test_fixture.read_text() != text:
+    if not test_fixture.exists() or test_fixture.read_text(encoding="utf-8") != text:
         changed = True
-        with test_fixture.open("w") as f:
+        with test_fixture.open("w", encoding="utf-8") as f:
             f.write(text)
         print(f"Also updated to {test_fixture}")
     else:
diff --git a/tests/test_cmark_spec/test_spec.py b/tests/test_cmark_spec/test_spec.py
index e5199477..b4becc25 100644
--- a/tests/test_cmark_spec/test_spec.py
+++ b/tests/test_cmark_spec/test_spec.py
@@ -15,10 +15,12 @@
 
 def test_file(file_regression):
     md = MarkdownIt("commonmark")
-    file_regression.check(md.render(SPEC_INPUT.read_text()), extension=".html")
+    file_regression.check(
+        md.render(SPEC_INPUT.read_text(encoding="utf-8")), extension=".html"
+    )
 
 
-@pytest.mark.parametrize("entry", json.loads(TESTS_INPUT.read_text()))
+@pytest.mark.parametrize("entry", json.loads(TESTS_INPUT.read_text(encoding="utf-8")))
 def test_spec(entry):
     md = MarkdownIt("commonmark")
     output = md.render(entry["markdown"])