diff --git a/mistral/db/v2/sqlalchemy/api.py b/mistral/db/v2/sqlalchemy/api.py
index a3f7ba85d..0c74e766d 100644
--- a/mistral/db/v2/sqlalchemy/api.py
+++ b/mistral/db/v2/sqlalchemy/api.py
@@ -21,7 +21,6 @@ from oslo_db import exception as db_exc
 from oslo_db import sqlalchemy as oslo_sqlalchemy
 from oslo_db.sqlalchemy import utils as db_utils
 from oslo_log import log as logging
-from oslo_utils import timeutils
 from oslo_utils import uuidutils
 import sqlalchemy as sa
 
@@ -96,20 +95,16 @@ def acquire_lock(model, id, session=None):
     # will be up-to-date from the DB and not from cache.
     session.expire_all()
 
-    if b.get_driver_name() != 'sqlite':
-        entity = _get_one_entity(model, id)
-        entity.update({'updated_at': timeutils.utcnow()})
-
-    else:
+    if b.get_driver_name() == 'sqlite':
+        # In case of 'sqlite' we need to apply a manual lock.
         sqlite_lock.acquire_lock(id, session)
-        entity = _get_one_entity(model, id)
 
-    return entity
+    return _lock_entity(model, id)
 
 
-def _get_one_entity(model, id):
-    # Get entity by ID and expect exactly one object.
-    return _secure_query(model).filter(model.id == id).one()
+def _lock_entity(model, id):
+    # Get entity by ID in "FOR UPDATE" mode and expect exactly one object.
+    return _secure_query(model).with_for_update().filter(model.id == id).one()
 
 
 def _secure_query(model, *columns):
diff --git a/mistral/workflow/base.py b/mistral/workflow/base.py
index d8662f854..21ccecccf 100644
--- a/mistral/workflow/base.py
+++ b/mistral/workflow/base.py
@@ -70,8 +70,8 @@ class WorkflowController(object):
         according to this workflow type rules and identifies a list of
         commands needed to continue the workflow.
 
-        :param: task_ex: Task execution to rerun.
-        :param: reset: If true, then purge action executions for the tasks.
+        :param task_ex: Task execution to rerun.
+        :param reset: If true, then purge action executions for the tasks.
         :param env: A set of environment variables to overwrite.
         :return: List of workflow commands (instances of
             mistral.workflow.commands.WorkflowCommand).
@@ -88,6 +88,7 @@ class WorkflowController(object):
     def is_error_handled_for(self, task_ex):
         """Determines if error is handled for specific task.
 
+        :param task_ex: Task execution perform a check for.
         :return: True if either there is no error at all or
             error is considered handled.
         """
diff --git a/tox.ini b/tox.ini
index 35a000148..43128bf55 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,7 +39,9 @@ commands =
     oslo-config-generator --config-file tools/config/config-generator.mistral.conf \
     --output-file etc/mistral.conf.sample
 
+#set PYTHONHASHSEED=0 to prevent wsmeext.sphinxext from randomly failing.
 [testenv:venv]
+setenv = PYTHONHASHSEED=0
 commands = {posargs}
 
 #set PYTHONHASHSEED=0 to prevent wsmeext.sphinxext from randomly failing.