diff --git a/tests/test_check.py b/tests/test_check.py
index 58bfbdfb..deda3409 100644
--- a/tests/test_check.py
+++ b/tests/test_check.py
@@ -58,11 +58,13 @@ def test_check_passing_distribution(monkeypatch):
     renderer = pretend.stub(
         render=pretend.call_recorder(lambda *a, **kw: "valid")
     )
-    package = pretend.stub(metadata_dictionary=lambda: {"description": "blah"})
+    package = pretend.stub(metadata_dictionary=lambda: {
+        "description": "blah", 'description_content_type': 'text/markdown',
+    })
     output_stream = check.StringIO()
     warning_stream = ""
 
-    monkeypatch.setattr(check, "_RENDERERS", {"": renderer})
+    monkeypatch.setattr(check, "_RENDERERS", {None: renderer})
     monkeypatch.setattr(check, "_find_dists", lambda a: ["dist/dist.tar.gz"])
     monkeypatch.setattr(
         check,
@@ -81,15 +83,41 @@ def test_check_passing_distribution(monkeypatch):
     ]
 
 
+def test_check_no_description(monkeypatch, capsys):
+    package = pretend.stub(metadata_dictionary=lambda: {
+        'description': None, 'description_content_type': None,
+    })
+
+    monkeypatch.setattr(check, "_find_dists", lambda a: ["dist/dist.tar.gz"])
+    monkeypatch.setattr(
+        check,
+        "PackageFile",
+        pretend.stub(from_filename=lambda *a, **kw: package),
+    )
+
+    # used to crash with `AttributeError`
+    output_stream = check.StringIO()
+    check.check("dist/*", output_stream=output_stream)
+    assert output_stream.getvalue() == (
+        'Checking distribution dist/dist.tar.gz: '
+        'warning: `long_description_content_type` missing.  '
+        'defaulting to `text/x-rst`.\n'
+        'warning: `long_description` missing.\n'
+        'Passed\n'
+    )
+
+
 def test_check_failing_distribution(monkeypatch):
     renderer = pretend.stub(
         render=pretend.call_recorder(lambda *a, **kw: None)
     )
-    package = pretend.stub(metadata_dictionary=lambda: {"description": "blah"})
+    package = pretend.stub(metadata_dictionary=lambda: {
+        "description": "blah", "description_content_type": 'text/markdown',
+    })
     output_stream = check.StringIO()
     warning_stream = "WARNING"
 
-    monkeypatch.setattr(check, "_RENDERERS", {"": renderer})
+    monkeypatch.setattr(check, "_RENDERERS", {None: renderer})
     monkeypatch.setattr(check, "_find_dists", lambda a: ["dist/dist.tar.gz"])
     monkeypatch.setattr(
         check,
diff --git a/twine/commands/check.py b/twine/commands/check.py
index 20377613..f71b2c90 100644
--- a/twine/commands/check.py
+++ b/twine/commands/check.py
@@ -33,7 +33,6 @@
 
 _RENDERERS = {
     None: readme_renderer.rst,  # Default if description_content_type is None
-    "": readme_renderer.rst,  # Default if description_content_type is None
     "text/plain": readme_renderer.txt,
     "text/x-rst": readme_renderer.rst,
     "text/markdown": readme_renderer.markdown,
@@ -85,28 +84,33 @@ def check(dists, output_stream=sys.stdout):
         package = PackageFile.from_filename(filename, comment=None)
 
         metadata = package.metadata_dictionary()
-        content_type, parameters = cgi.parse_header(
-            metadata.get("description_content_type") or ""
-        )
-
-        # Get the appropriate renderer
-        renderer = _RENDERERS.get(content_type, readme_renderer.txt)
-
-        # Actually render the given value
-        rendered = renderer.render(
-            metadata.get("description"), stream=stream, **parameters
-        )
+        description = metadata["description"]
+        description_content_type = metadata["description_content_type"]
 
-        if rendered is None:
-            failure = True
-            output_stream.write("Failed\n")
+        if description_content_type is None:
             output_stream.write(
-                "The project's long_description has invalid markup which will "
-                "not be rendered on PyPI. The following syntax errors were "
-                "detected:\n%s" % stream
+                'warning: `long_description_content_type` missing.  '
+                'defaulting to `text/x-rst`.\n'
             )
-        else:
+            description_content_type = 'text/x-rst'
+
+        content_type, params = cgi.parse_header(description_content_type)
+        renderer = _RENDERERS.get(content_type, _RENDERERS[None])
+
+        if description in {None, 'UNKNOWN\n\n\n'}:
+            output_stream.write('warning: `long_description` missing.\n')
             output_stream.write("Passed\n")
+        else:
+            if renderer.render(description, stream=stream, **params) is None:
+                failure = True
+                output_stream.write("Failed\n")
+                output_stream.write(
+                    "The project's long_description has invalid markup which "
+                    "will not be rendered on PyPI. The following syntax "
+                    "errors were detected:\n%s" % stream
+                )
+            else:
+                output_stream.write("Passed\n")
 
     return failure