diff --git a/capa/features/extractors/viv/helpers.py b/capa/features/extractors/viv/helpers.py
index 7163cc79..f3cdb963 100644
--- a/capa/features/extractors/viv/helpers.py
+++ b/capa/features/extractors/viv/helpers.py
@@ -5,10 +5,13 @@
 # Unless required by applicable law or agreed to in writing, software distributed under the License
 #  is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and limitations under the License.
+from typing import Optional
+
+from vivisect import VivWorkspace
 from vivisect.const import XR_TO, REF_CODE
 
 
-def get_coderef_from(vw, va):
+def get_coderef_from(vw: VivWorkspace, va: int) -> Optional[int]:
     """
     return first code `tova` whose origin is the specified va
     return None if no code reference is found
diff --git a/setup.py b/setup.py
index 354f07fd..b0e3a496 100644
--- a/setup.py
+++ b/setup.py
@@ -75,7 +75,7 @@ setuptools.setup(
         ],
         "mypy": [
             "types-colorama",
-        ]
+        ],
     },
     zip_safe=False,
     keywords="capa malware analysis capability detection FLARE",