diff --git a/board/lwmon/lwmon.c b/board/lwmon/lwmon.c
index e797b36..f255599 100644
--- a/board/lwmon/lwmon.c
+++ b/board/lwmon/lwmon.c
@@ -833,7 +833,7 @@
 }
 
 /* Read and set LSB switch */
-#define CFG_PC_TXD1_ENA		0x0008
+#define CFG_PC_TXD1_ENA		0x0008		/* PC.12 */
 
 /***********************************************************************
 F* Function:     int do_lsb (cmd_tbl_t *cmdtp, int flag,