diff --git a/assess_constraints.py b/assess_constraints.py
index <HASH>..<HASH> 100755
--- a/assess_constraints.py
+++ b/assess_constraints.py
@@ -155,8 +155,7 @@ def assess_instance_type_constraints(client):
     """Assess deployment with instance-type constraints."""
     provider = client.env.config.get('type')
     if provider not in INSTANCE_TYPES:
-        raise ValueError('Provider does not implement instance-type '
-                         'constraint.')
+        return
     for instance_type in INSTANCE_TYPES[provider]:
         assess_instance_type(client, provider, instance_type)
 
diff --git a/tests/test_assess_constraints.py b/tests/test_assess_constraints.py
index <HASH>..<HASH> 100644
--- a/tests/test_assess_constraints.py
+++ b/tests/test_assess_constraints.py
@@ -124,8 +124,9 @@ class TestAssess(TestCase):
 
     def test_instance_type_constraints_missing(self):
         fake_client = Mock(wraps=fake_juju_client())
-        with self.assertRaises(ValueError):
+        with self.prepare_deploy_mock() as (fake_client, deploy_mock):
             assess_instance_type_constraints(fake_client)
+        self.assertFalse(deploy_mock.called)
 
 
 class TestDeploy(TestCase):
Made testing a provider with no instance-types a no-op for assess_instance_type_constraints rather than an error.