diff --git a/api/core/workflow/nodes/tool/tool_node.py b/api/core/workflow/nodes/tool/tool_node.py
index 9b52cd2f6b..ccce9ef360 100644
--- a/api/core/workflow/nodes/tool/tool_node.py
+++ b/api/core/workflow/nodes/tool/tool_node.py
@@ -2,7 +2,7 @@ from collections.abc import Mapping, Sequence
 from os import path
 from typing import Any, cast
 
-from core.app.segments import ArrayAnyVariable, parser
+from core.app.segments import ArrayAnySegment, ArrayAnyVariable, parser
 from core.callback_handler.workflow_tool_callback_handler import DifyWorkflowCallbackHandler
 from core.file.file_obj import FileTransferMethod, FileType, FileVar
 from core.tools.entities.tool_entities import ToolInvokeMessage, ToolParameter
@@ -142,7 +142,7 @@ class ToolNode(BaseNode):
 
     def _fetch_files(self, variable_pool: VariablePool) -> list[FileVar]:
         variable = variable_pool.get(['sys', SystemVariableKey.FILES.value])
-        assert isinstance(variable, ArrayAnyVariable)
+        assert isinstance(variable, ArrayAnyVariable | ArrayAnySegment)
         return list(variable.value) if variable else []
 
     def _convert_tool_messages(self, messages: list[ToolInvokeMessage]):