diff --git a/tests/test_check.py b/tests/test_check.py
index 66809ccf..cd722adc 100644
--- a/tests/test_check.py
+++ b/tests/test_check.py
@@ -107,10 +107,11 @@ def test_check_passing_distribution_with_none_renderer(
     assert capsys.readouterr().out == "Checking dist/dist.tar.gz: PASSED\n"
 
 
-def test_check_no_description(monkeypatch, capsys, caplog):
+@pytest.mark.parametrize("description", [None, "UNKNOWN\n\n", "UNKNOWN\n\n\n"])
+def test_check_no_description(description, monkeypatch, capsys, caplog):
     package = pretend.stub(
         metadata_dictionary=lambda: {
-            "description": None,
+            "description": description,
             "description_content_type": None,
         }
     )
diff --git a/twine/commands/check.py b/twine/commands/check.py
index d4f0f25f..faefeb69 100644
--- a/twine/commands/check.py
+++ b/twine/commands/check.py
@@ -93,7 +93,7 @@ def _check_file(
     content_type, params = cgi.parse_header(description_content_type)
     renderer = _RENDERERS.get(content_type, _RENDERERS[None])
 
-    if description in {None, "UNKNOWN\n\n\n"}:
+    if description is None or description.rstrip("\n") == "UNKNOWN":
         warnings.append("`long_description` missing.")
     elif renderer:
         rendering_result = renderer.render(