diff --git a/api/core/workflow/nodes/tool/tool_node.py b/api/core/workflow/nodes/tool/tool_node.py
index 5c6fac9080c976..48627a229df249 100644
--- a/api/core/workflow/nodes/tool/tool_node.py
+++ b/api/core/workflow/nodes/tool/tool_node.py
@@ -329,6 +329,7 @@ def _transform_message(
                             icon = current_plugin.declaration.icon
                         except StopIteration:
                             pass
+                        icon_dark = None
                         try:
                             builtin_tool = next(
                                 provider