diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 95816d8f..366fb849 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -37,6 +37,11 @@ jobs:
       run: |
         mypy --config-file=./mypy.ini -p responses
 
+    - name: Run mypy (namespace packages)
+      run: |
+        # see https://github.com/getsentry/responses/issues/556
+        mypy --config-file=./mypy.ini --namespace-packages -p responses
+
   tests:
     runs-on: ubuntu-latest
     strategy:
diff --git a/setup.py b/setup.py
index 33b3bef1..aa01e3fd 100644
--- a/setup.py
+++ b/setup.py
@@ -29,7 +29,6 @@
     "pytest-asyncio",
     "pytest-localserver",
     "flake8",
-    "types-mock",
     "types-requests",
     "mypy",
 ]