diff --git a/os/hal/boards/SIPEED_LONGAN_NANO/board.c b/os/hal/boards/SIPEED_LONGAN_NANO/board.c
index 6bf05ce0..36a27cb5 100644
--- a/os/hal/boards/SIPEED_LONGAN_NANO/board.c
+++ b/os/hal/boards/SIPEED_LONGAN_NANO/board.c
@@ -44,4 +44,6 @@ void __early_init(void) {
  * Board-specific initialization code.
  */
 void boardInit(void) {
+    /* Free B4 pin by disabling JTAG NJTRST. */
+    AFIO->PCF0 |= AFIO_PCF0_SWJ_CFG_NOJNTRST;
 }