diff --git a/firmware/config/boards/f407-discovery/board.mk b/firmware/config/boards/f407-discovery/board.mk
index 98004cc263..6ddbf50492 100644
--- a/firmware/config/boards/f407-discovery/board.mk
+++ b/firmware/config/boards/f407-discovery/board.mk
@@ -22,6 +22,10 @@ DDEFS += -DFLEXIBLE_CRITICAL_LED=1
 DDEFS += -DHW_FRANKENSO=1
 DDEFS += $(DEFAULT_ENGINE_TYPE)
 
+# TS_SECONDARY_UxART_PORT
+DDEFS += -DSTM32_SERIAL_USE_USART3=TRUE
+DDEFS += -DTS_SECONDARY_UxART_PORT=SD3
+
 DDEFS += -DSTM32_I2C_USE_I2C3=TRUE
 
 ifndef IS_RE_BOOTLOADER