diff --git a/.ci/azure-pipelines.yml b/.ci/azure-pipelines.yml
index 4513ae9f..073095b8 100644
--- a/.ci/azure-pipelines.yml
+++ b/.ci/azure-pipelines.yml
@@ -33,13 +33,9 @@ jobs:
 
       # NOTE: this hangs when ran in Ubuntu 18.04
       Van_27_210:
-        tox.env: py27-mode_localhost-ansible2.10
-        STRATEGY: linear
-        ANSIBLE_SKIP_TAGS: resource_intensive
+        tox.env: py27-mode_localhost-ansible2.10-strategy_linear
       Van_27_4:
-        tox.env: py27-mode_localhost-ansible4
-        STRATEGY: linear
-        ANSIBLE_SKIP_TAGS: resource_intensive
+        tox.env: py27-mode_localhost-ansible4-strategy_linear
 
 - job: Linux
   pool:
diff --git a/ansible_mitogen/process.py b/ansible_mitogen/process.py
index 63caa88a..d3e6abdc 100644
--- a/ansible_mitogen/process.py
+++ b/ansible_mitogen/process.py
@@ -185,9 +185,6 @@ def _setup_responder(responder):
     Configure :class:`mitogen.master.ModuleResponder` to only permit
     certain packages, and to generate custom responses for certain modules.
     """
-    responder.whitelist_prefix('ansible')
-    responder.whitelist_prefix('ansible_mitogen')
-
     # Ansible 2.3 is compatible with Python 2.4 targets, however
     # ansible/__init__.py is not. Instead, executor/module_common.py writes
     # out a 2.4-compatible namespace package for unknown reasons. So we
diff --git a/tests/ansible/integration/all.yml b/tests/ansible/integration/all.yml
index ac196584..47d98cce 100644
--- a/tests/ansible/integration/all.yml
+++ b/tests/ansible/integration/all.yml
@@ -29,6 +29,8 @@
   tags: playbook_semantics
 - import_playbook: process/all.yml
   tags: process
+- import_playbook: responder/all.yml
+  tags: responder
 - import_playbook: runner/all.yml
   tags: runner
 - import_playbook: ssh/all.yml
diff --git a/tests/ansible/integration/responder/all.yml b/tests/ansible/integration/responder/all.yml
new file mode 100644
index 00000000..5846bcd9
--- /dev/null
+++ b/tests/ansible/integration/responder/all.yml
@@ -0,0 +1 @@
+- import_playbook: imports.yml
diff --git a/tests/ansible/integration/responder/imports.yml b/tests/ansible/integration/responder/imports.yml
new file mode 100644
index 00000000..42edb8f3
--- /dev/null
+++ b/tests/ansible/integration/responder/imports.yml
@@ -0,0 +1,23 @@
+- name: integration/responder/imports.yml
+  hosts: test-targets
+  tasks:
+    - meta: end_play
+      when: not is_mitogen
+
+    - name: Import pure Python module via Ansible module
+      mitogen_plain_old_add:
+        x: 2
+        y: 2
+      register: mitogen_plain_old_add_result
+
+    - name: Import binary module via Responder
+      custom_python_run_script:
+        script: |
+          import lxml
+      register: binary_module_result
+
+    - name: Import missing module via Responder
+      custom_python_run_script:
+        script: |
+          import does_not_exist
+      register: missing_module_result
diff --git a/tests/ansible/lib/modules/mitogen_plain_old_add.py b/tests/ansible/lib/modules/mitogen_plain_old_add.py
new file mode 100644
index 00000000..19f3b9ee
--- /dev/null
+++ b/tests/ansible/lib/modules/mitogen_plain_old_add.py
@@ -0,0 +1,36 @@
+#!/usr/bin/env python
+
+DOCUMENTATION = '''
+module: mitogen_plain_old_add
+options:
+    x: {type: int, required: true}
+    y: {type: int, required: true}
+author:
+    - Alex Willmer (@moreati)
+'''
+
+RETURN = '''
+total: {type: int, returned: always, sample: 42}
+'''
+
+from ansible.module_utils.basic import AnsibleModule
+
+import plain_old_module
+
+def main():
+    module = AnsibleModule(
+        argument_spec={
+            'x': {'type': int, 'required': True},
+            'x': {'type': int, 'required': True},
+        },
+        supports_check_mode=True,
+    )
+    result = {
+        'changed': False,
+        'total': plain_old_module.add(module.params['x'], module.params['y']),
+    }
+    module.exit_json(**result)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tests/ansible/run_ansible_playbook.py b/tests/ansible/run_ansible_playbook.py
index 04c0c9db..bda9ca15 100755
--- a/tests/ansible/run_ansible_playbook.py
+++ b/tests/ansible/run_ansible_playbook.py
@@ -35,6 +35,8 @@ os.environ['PATH'] = '%s%s%s' % (
     os.environ['PATH'],
 )
 
+os.environ['PYTHONPATH'] = os.path.join(GIT_BASEDIR, 'tests', 'data')
+
 extra = {
     'is_mitogen': os.environ.get('ANSIBLE_STRATEGY', '').startswith('mitogen'),
     'git_basedir': GIT_BASEDIR,