diff --git a/src/helpers/esp32/WdtHeavyGuard.h b/src/helpers/esp32/WdtHeavyGuard.h
index b8d0c34..8e6d646 100644
--- a/src/helpers/esp32/WdtHeavyGuard.h
+++ b/src/helpers/esp32/WdtHeavyGuard.h
@@ -38,6 +38,7 @@ inline void wdtHeavyEnd()   { int& d = _wdtHeavyDepth(); if (d > 0 && --d == 0)
 // work instead of silently arming a new watchdog on the way out. The guard can
 // be constructed by a storage worker, so query Arduino's loopTask handle rather
 // than `nullptr` (which means the current worker task to ESP-IDF).
+#if defined(CONFIG_AUTOSTART_ARDUINO)
 extern TaskHandle_t loopTaskHandle;
 struct LoopWdtGuard {
   bool subscribed;
@@ -50,6 +51,11 @@ struct LoopWdtGuard {
   }
 };
 #else
+// Tanmatsu and T-Display-P4 supply app_main() themselves. Their Arduino
+// component has no loopTaskHandle or loop-WDT helpers to preserve.
+struct LoopWdtGuard {};
+#endif
+#else
 inline void wdtHeavyBegin() {}
 inline void wdtHeavyEnd()   {}
 struct LoopWdtGuard {};