diff --git a/tests/docker/dirty_ttin_ttou/Dockerfile b/tests/docker/dirty_ttin_ttou/Dockerfile
index 7d6c66ae..0c6cd837 100644
--- a/tests/docker/dirty_ttin_ttou/Dockerfile
+++ b/tests/docker/dirty_ttin_ttou/Dockerfile
@@ -6,9 +6,11 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 WORKDIR /app
 
-# Install gunicorn from source
+# Install gunicorn from source.  setproctitle is required so dirty-arbiter
+# and dirty-worker processes get distinguishable names that the tests use
+# to count workers via pgrep.
 COPY . /gunicorn-src/
-RUN pip install --no-cache-dir /gunicorn-src/
+RUN pip install --no-cache-dir /gunicorn-src/ setproctitle
 
 # Copy test app
 COPY tests/docker/dirty_ttin_ttou/app.py /app/
diff --git a/tests/docker/dirty_ttin_ttou/test_ttin_ttou_docker.py b/tests/docker/dirty_ttin_ttou/test_ttin_ttou_docker.py
index ca72c26d..9efcffff 100644
--- a/tests/docker/dirty_ttin_ttou/test_ttin_ttou_docker.py
+++ b/tests/docker/dirty_ttin_ttou/test_ttin_ttou_docker.py
@@ -21,7 +21,10 @@ pytestmark = [
 # Directory containing this test file
 TEST_DIR = Path(__file__).parent
 COMPOSE_FILE = TEST_DIR / "docker-compose.yml"
-BASE_URL = "http://localhost:18000"
+# Use 127.0.0.1 (not "localhost") so we always hit IPv4. Docker Desktop /
+# OrbStack on macOS map host ports to IPv4 only, and ``localhost`` resolves
+# to ``::1`` on this host, which yields connection-reset noise.
+BASE_URL = "http://127.0.0.1:18000"
 
 
 @pytest.fixture(scope="module")
diff --git a/tests/docker/per_app_allocation/README.md b/tests/docker/per_app_allocation/README.md
index bae552d7..91535227 100644
--- a/tests/docker/per_app_allocation/README.md
+++ b/tests/docker/per_app_allocation/README.md
@@ -58,5 +58,5 @@ pytest test_per_app_e2e.py::TestPerAppAllocation::test_config_limited_app_uses_o
 
 ## Notes
 
-- Tests run on port 8001 to avoid conflicts with the existing dirty_arbiter tests on 8000
+- Tests run on port 28001 to avoid conflicts with the existing dirty_arbiter tests on 8000 and with macOS Docker alternatives that often reserve port 8001 (e.g., OrbStack's vcom-tunnel)
 - The container uses a keep-alive wrapper to allow testing worker crash scenarios
diff --git a/tests/docker/per_app_allocation/docker-compose.yml b/tests/docker/per_app_allocation/docker-compose.yml
index 19aaf7c8..a389cd0b 100644
--- a/tests/docker/per_app_allocation/docker-compose.yml
+++ b/tests/docker/per_app_allocation/docker-compose.yml
@@ -4,7 +4,7 @@ services:
       context: ../../..
       dockerfile: tests/docker/per_app_allocation/Dockerfile
     ports:
-      - "8001:8000"
+      - "28001:8000"
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:8000/status"]
       interval: 1s
diff --git a/tests/docker/per_app_allocation/test_per_app_e2e.py b/tests/docker/per_app_allocation/test_per_app_e2e.py
index 1abcb1b3..e1c34472 100644
--- a/tests/docker/per_app_allocation/test_per_app_e2e.py
+++ b/tests/docker/per_app_allocation/test_per_app_e2e.py
@@ -39,7 +39,7 @@ class DockerContainer:
         self.name = name
         self.build = build
         self.container_id = None
-        self.base_url = "http://127.0.0.1:8001"
+        self.base_url = "http://127.0.0.1:28001"
 
     def __enter__(self):
         # Build if requested
@@ -64,7 +64,7 @@ class DockerContainer:
             [
                 "docker", "run", "-d",
                 "--name", self.name,
-                "-p", "8001:8000",
+                "-p", "28001:8000",
                 "per_app_allocation-gunicorn",
                 "sh", "-c",
                 "gunicorn app:application -c gunicorn_conf.py & "