diff --git a/climate/context.py b/climate/context.py
index e0c56064..d3bbb410 100644
--- a/climate/context.py
+++ b/climate/context.py
@@ -43,6 +43,15 @@ class BaseContext(object):
             else:
                 raise AttributeError(name)
 
+    def __setattr__(self, name, value):
+        # NOTE(yorik-sar): only the very first assignment for __values is
+        # allowed. All context arguments should be set at the time the context
+        # object is being created.
+        if not self.__dict__:
+            super(BaseContext, self).__setattr__(name, value)
+        else:
+            raise Exception(self.__dict__, name, value)
+
     def __enter__(self):
         try:
             stack = self._context_stack.stack
diff --git a/climate/tests/utils/test_trusts.py b/climate/tests/utils/test_trusts.py
index a3c7f5eb..716d529d 100644
--- a/climate/tests/utils/test_trusts.py
+++ b/climate/tests/utils/test_trusts.py
@@ -51,12 +51,13 @@ class TestTrusts(tests.TestCase):
 
     def test_create_ctx_from_trust(self):
         fake_item = self.client().service_catalog.catalog.__getitem__()
-        fake_ctx_dict = {'_BaseContext__values': {},
-                         'auth_token': self.client().auth_token,
-                         'service_catalog': fake_item,
-                         'tenant_id': self.client().tenant_id,
-                         'tenant_name': 'admin',
-                         'user_name': 'admin'}
+        fake_ctx_dict = {'_BaseContext__values': {
+            'auth_token': self.client().auth_token,
+            'service_catalog': fake_item,
+            'tenant_id': self.client().tenant_id,
+            'tenant_name': 'admin',
+            'user_name': 'admin',
+        }}
 
         ctx = self.trusts.create_ctx_from_trust('1')
 
diff --git a/climate/utils/trusts.py b/climate/utils/trusts.py
index f134027f..b87117ff 100644
--- a/climate/utils/trusts.py
+++ b/climate/utils/trusts.py
@@ -48,9 +48,10 @@ def delete_trust(lease):
 
 def create_ctx_from_trust(trust_id):
     """Return context built from given trust."""
-    ctx = context.ClimateContext()
-    ctx.user_name = CONF.os_admin_username
-    ctx.tenant_name = CONF.os_admin_tenant_name
+    ctx = context.ClimateContext(
+        user_name=CONF.os_admin_username,
+        tenant_name=CONF.os_admin_tenant_name,
+    )
     auth_url = "%s://%s:%s/v3" % (CONF.os_auth_protocol,
                                   CONF.os_auth_host,
                                   CONF.os_auth_port)
@@ -58,12 +59,13 @@ def create_ctx_from_trust(trust_id):
         password=CONF.os_admin_password,
         trust_id=trust_id,
         auth_url=auth_url,
-        ctx=ctx
+        ctx=ctx,
     )
 
-    ctx.auth_token = client.auth_token
-    ctx.service_catalog = client.service_catalog.catalog['catalog']
-    ctx.tenant_id = client.tenant_id
-
     # use 'with ctx' statement in the place you need context from trust
-    return ctx
+    return context.ClimateContext(
+        ctx,
+        auth_token=client.auth_token,
+        service_catalog=client.service_catalog.catalog['catalog'],
+        tenant_id=client.tenant_id,
+    )