diff --git a/taskflow/engines/action_engine/executor.py b/taskflow/engines/action_engine/executor.py
index b2bdbdae..40a671eb 100644
--- a/taskflow/engines/action_engine/executor.py
+++ b/taskflow/engines/action_engine/executor.py
@@ -19,6 +19,7 @@ import abc
 from concurrent import futures
 import six
 
+from taskflow import task as _task
 from taskflow.utils import async_utils
 from taskflow.utils import misc
 from taskflow.utils import threading_utils
@@ -44,8 +45,8 @@ def _execute_task(task, arguments, progress_callback):
 
 def _revert_task(task, arguments, result, failures, progress_callback):
     kwargs = arguments.copy()
-    kwargs['result'] = result
-    kwargs['flow_failures'] = failures
+    kwargs[_task.REVERT_RESULT] = result
+    kwargs[_task.REVERT_FLOW_FAILURES] = failures
     with task.autobind('update_progress', progress_callback):
         try:
             task.pre_revert()
diff --git a/taskflow/task.py b/taskflow/task.py
index cd470e72..211f09cc 100644
--- a/taskflow/task.py
+++ b/taskflow/task.py
@@ -27,6 +27,14 @@ from taskflow.utils import reflection
 
 LOG = logging.getLogger(__name__)
 
+# Constants passed into revert kwargs.
+#
+# Contain the execute() result (if any).
+REVERT_RESULT = 'result'
+#
+# The cause of the flow failure/s
+REVERT_FLOW_FAILURES = 'flow_failures'
+
 
 @six.add_metaclass(abc.ABCMeta)
 class BaseTask(atom.Atom):