diff --git a/lib/stm32/f1/can.c b/lib/stm32/f1/can.c
index 151c47cd..fc7e0e75 100644
--- a/lib/stm32/f1/can.c
+++ b/lib/stm32/f1/can.c
@@ -228,7 +228,7 @@ int can_transmit(u32 canport, u32 id, bool ext, bool rtr, u8 length, u8 *data)
 		CAN_TIxR(canport, mailbox) |= CAN_TIxR_RTR; /* Set */
 
 	/* Set the DLC. */
-	CAN_TDTxR(canport, mailbox) &= 0xFFFFFFFF0;
+	CAN_TDTxR(canport, mailbox) &= 0xFFFFFFF0;
 	CAN_TDTxR(canport, mailbox) |= length & CAN_TDTxR_DLC_MASK;
 
 	/* Set the data. */