diff --git a/readme_renderer/clean.py b/readme_renderer/clean.py
index a93b6f8..b081e28 100644
--- a/readme_renderer/clean.py
+++ b/readme_renderer/clean.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from typing import Dict, List, Optional, Set
+from typing import Dict, Optional, Set
 
 import nh3
 
diff --git a/tests/fixtures/test_GFM_024.html b/tests/fixtures/test_GFM_024.html
index df9cabe..b5f9d02 100644
--- a/tests/fixtures/test_GFM_024.html
+++ b/tests/fixtures/test_GFM_024.html
@@ -1,17 +1,17 @@
 <ul>
-<li><input type="checkbox" disabled> Valid unchecked checkbox</li>
-<li><input type="checkbox" checked disabled> Valid checked checkbox</li>
-<li> Invalid enabled checkbox</li>
+<li><input type="checkbox" disabled=""> Valid unchecked checkbox</li>
+<li><input type="checkbox" checked="" disabled=""> Valid checked checkbox</li>
+<li><input type="checkbox"> Invalid enabled checkbox</li>
 <li>
-
+<input>
 </li>
 <li>
-
+<input type="submit">
 </li>
 <li>
-
+<input>
 </li>
 <li>
-
+<input type="checkbox" checked="">
 </li>
 </ul>