diff --git a/unit_tests/test_zaza_model.py b/unit_tests/test_zaza_model.py
index fb112d9..df5c068 100644
--- a/unit_tests/test_zaza_model.py
+++ b/unit_tests/test_zaza_model.py
@@ -91,6 +91,8 @@ class TestModel(ut_utils.BaseTestCase):
         self.unit2.run_action.side_effect = _run_action
         self.unit1.is_leader_from_status.side_effect = _is_leader(False)
         self.unit2.is_leader_from_status.side_effect = _is_leader(True)
+        self.unit1.data = {'agent-status': {'current': 'idle'}}
+        self.unit2.data = {'agent-status': {'current': 'idle'}}
         self.units = [self.unit1, self.unit2]
         self.relation1 = mock.MagicMock()
         self.relation1.id = 42
@@ -893,6 +895,29 @@ disk_formats = ami,ari,aki,vhd,vmdk,raw,qcow2,vdi,iso,root-tar
                 'active',
                 timeout=0.1)
 
+    def test_wait_for_agent_status(self):
+        async def _block_until(f, timeout=None):
+            if not f():
+                raise asyncio.futures.TimeoutError
+        self.patch_object(model, 'get_juju_model', return_value='mname')
+        self.patch_object(model, 'Model')
+        self.unit1.data = {'agent-status': {'current': 'idle'}}
+        self.unit2.data = {'agent-status': {'current': 'executing'}}
+        self.Model.return_value = self.Model_mock
+        self.Model_mock.block_until.side_effect = _block_until
+        model.wait_for_agent_status(timeout=0.1)
+
+    def test_wait_for_agent_status_timeout(self):
+        async def _block_until(f, timeout=None):
+            if not f():
+                raise asyncio.futures.TimeoutError
+        self.patch_object(model, 'get_juju_model', return_value='mname')
+        self.patch_object(model, 'Model')
+        self.Model.return_value = self.Model_mock
+        self.Model_mock.block_until.side_effect = _block_until
+        with self.assertRaises(asyncio.futures.TimeoutError):
+            model.wait_for_agent_status(timeout=0.1)
+
 
 class AsyncModelTests(aiounittest.AsyncTestCase):
 
diff --git a/zaza/charm_tests/test_utils.py b/zaza/charm_tests/test_utils.py
index 5917f63..8b40e74 100644
--- a/zaza/charm_tests/test_utils.py
+++ b/zaza/charm_tests/test_utils.py
@@ -77,6 +77,10 @@ class OpenStackBaseTest(unittest.TestCase):
             alternate_config,
             model_name=self.model_name)
 
+        logging.debug(
+            'Waiting for units to execute config-changed hook')
+        model.wait_for_agent_status(model_name=self.model_name)
+
         logging.debug(
             'Waiting for units to reach target states')
         model.wait_for_application_states(
diff --git a/zaza/model.py b/zaza/model.py
index 6a89720..4fe1277 100644
--- a/zaza/model.py
+++ b/zaza/model.py
@@ -606,6 +606,42 @@ def check_unit_workload_status_message(model, unit, message=None,
         raise ValueError("Must be called with message or prefixes")
 
 
+async def async_wait_for_agent_status(model_name=None, status='executing',
+                                      timeout=60):
+    """Wait for at least one unit to enter a specific agent status.
+
+    This is useful for awaiting execution after mutating charm configuration.
+
+    :param model_name: Name of model to query.
+    :type model_name: str
+    :param status: The desired agent status we are looking for.
+    :type status: str
+    :param timeout: Time to wait for status to be achieved.
+    :type timeout: int
+    """
+    def one_agent_status(model, status):
+        check_model_for_hard_errors(model)
+        for app in model.applications:
+            for unit in model.applications[app].units:
+                agent_status = unit.data.get('agent-status', {})
+                if agent_status.get('current', None) == status:
+                    break
+            else:
+                continue
+            break
+        else:
+            return False
+        return True
+
+    async with run_in_model(model_name) as model:
+        logging.info('Waiting for at least one unit with agent status "{}"'
+                     .format(status))
+        await model.block_until(
+            lambda: one_agent_status(model, status), timeout=timeout)
+
+wait_for_agent_status = sync_wrapper(async_wait_for_agent_status)
+
+
 async def async_wait_for_application_states(model_name=None, states=None,
                                             timeout=2700):
     """Wait for model to achieve the desired state.