diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 2cfaada3..a8eef614 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -43,9 +43,9 @@ jobs:
       run: |
         nox -s unit${{ matrix.option }}-${{ matrix.python }}
     - name: Upload coverage results
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       with:
-        name: coverage-artifacts
+        name: coverage-artifact-${{ matrix.option }}-${{ matrix.python }}
         path: .coverage${{ matrix.option }}-${{ matrix.python }}
 
   report-coverage:
@@ -65,11 +65,11 @@ jobs:
         python -m pip install --upgrade setuptools pip wheel
         python -m pip install coverage
     - name: Download coverage results
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
-        name: coverage-artifacts
         path: .coverage-results/
     - name: Report coverage results
       run: |
-        coverage combine .coverage-results/.coverage*
+        find .coverage-results -type f -name '*.zip' -exec unzip {} \;
+        coverage combine .coverage-results/**/.coverage*
         coverage report --show-missing --fail-under=100
diff --git a/noxfile.py b/noxfile.py
index 2c7ec6c7..8fbcaec0 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -175,12 +175,12 @@ def pytype(session):
 def mypy(session):
     """Run type-checking."""
     session.install(".[grpc]", "mypy")
-    # Exclude types-protobuf==4.24.0.20240106
-    # See https://github.com/python/typeshed/issues/11254
     session.install(
         "types-setuptools",
         "types-requests",
-        "types-protobuf!=4.24.0.20240106",
+        # TODO(https://github.com/googleapis/python-api-core/issues/642):
+        # Use the latest version of types-protobuf.
+        "types-protobuf<5",
         "types-mock",
         "types-dataclasses",
     )