diff --git a/backend/workflow_executor.py b/backend/workflow_executor.py
index 4b99bde..e00a423 100644
--- a/backend/workflow_executor.py
+++ b/backend/workflow_executor.py
@@ -18,7 +18,7 @@ import json
 from jinja2 import Environment, ChainableUndefined, TemplateError
 
 from workflow_models import (
-    WorkflowGraph, NodeExecutionState, ExecutionResult,
+    WorkflowGraph, WorkflowNode, NodeExecutionState, ExecutionResult,
     NodeStatus, NormalizedSignal, FallbackStrategy, SignalStatus,
     EndNodeOutputMode
 )