diff --git a/FluidNC/src/ToolChangers/atc.h b/FluidNC/src/ToolChangers/atc.h
index 184346244..9902c8565 100644
--- a/FluidNC/src/ToolChangers/atc.h
+++ b/FluidNC/src/ToolChangers/atc.h
@@ -33,7 +33,7 @@ namespace ATCs {
         virtual void probe_notification();
         virtual bool tool_change(uint8_t value, bool pre_select, bool set_tool) = 0;
 
-        ATC* __atc;
+        ATC* _atc;
 
         // Configuration handlers:
         void validate() override {}