diff --git a/avr/modules/flash/io_attn.asm b/avr/modules/flash/io_attn.asm
index 5454b19..1332ff6 100644
--- a/avr/modules/flash/io_attn.asm
+++ b/avr/modules/flash/io_attn.asm
@@ -26,6 +26,9 @@ ioWaitForAttnState100ms:
   cbi COM_ATTN_DDR, COM_ATTN_PIN          ; set ATTN port as input
   cbi COM_ATTN_OUTPUT, COM_ATTN_PIN       ; disable internal pullup for ATTN
 ioWaitForAttnState100ms_loop:
+#ifdef LED_SIMPLE_PINNUM
+    sbi LED_SIMPLE_PORTIN, LED_SIMPLE_PINNUM  ; toggle LED
+#endif
     push r17
       ldi r17, 100
       rcall ioWaitForAttnStateMilliSeconds          ; (R22, R24)