diff --git a/src/machine/board_hifive1b.go b/src/machine/board_hifive1b.go
index 5ce9d7ca..ff5b4022 100644
--- a/src/machine/board_hifive1b.go
+++ b/src/machine/board_hifive1b.go
@@ -37,8 +37,8 @@ const (
 
 const (
 	// TODO: figure out the pin numbers for these.
-	UART_TX_PIN = NoPin
-	UART_RX_PIN = NoPin
+	UART_TX_PIN = D1
+	UART_RX_PIN = D0
 )
 
 // SPI pins