diff --git a/board/nm/nmhw21/mux.c b/board/nm/nmhw21/mux.c
index 9a8b101dc9..38fced9a5f 100644
--- a/board/nm/nmhw21/mux.c
+++ b/board/nm/nmhw21/mux.c
@@ -38,7 +38,7 @@ static struct module_pin_mux gpio_pin_mux[] = {
 	* (T16) GPIO1_26: WLAN_EN
 	* (V17) GPIO1_27: WLAN_IRQ
 	*
-	* (U3) GPIO2_16: TIMEPULSE (HW26)
+	* (U3) GPIO2_16: TIMEPULSE (HW26), see note [1]
 	* (R6) GPIO2_25: RST_ETH~
 	*
 	* (J17) GPIO3_4: GNSS_EXTINT
@@ -46,6 +46,9 @@ static struct module_pin_mux gpio_pin_mux[] = {
 	* (L18) GPIO3_10: CTRL.RST
 	* (C12) GPIO3_17: UI_RST~
 	* (A14) GPIO3_21: RST_HUB~ (USB)
+	*
+	* [1] No PU/PD allowed as TIMEPULSE is internally connected with SAFEBOOT_N.
+	*     SAFEBOOT_N must be left open/floating.
 	*/
 
 	/* Bank 0 */
@@ -65,7 +68,7 @@ static struct module_pin_mux gpio_pin_mux[] = {
 	{OFFSET(gpmc_a11), (MODE(7) | PULLUDDIS | RXACTIVE)},			/* (V17) gpio1_27: WLAN_IRQ */
 
 	/* Bank 2 */
-	{OFFSET(lcd_data10), (MODE(7) | PULLUDEN | PULLDOWN_EN | RXACTIVE)},	/* (U3) GPIO2_16: TIMEPULSE input */
+	{OFFSET(lcd_data10), (MODE(7) | PULLUDDIS | RXACTIVE)},			/* (U3) GPIO2_16: TIMEPULSE */
 	{OFFSET(lcd_ac_bias_en), (MODE(7) | PULLUDDIS)},			/* (R6) GPIO2_25: RST_ETH~ */
 
 	/* Bank 3 */
@@ -215,8 +218,8 @@ static struct module_pin_mux uart2_pin_mux[] = {
 
 /* UART3: GNSS */
 static struct module_pin_mux uart3_pin_mux[] = {
-	{OFFSET(mii1_rxd3), (MODE(1) | PULLUDEN | PULLUP_EN | RXACTIVE)},	/* (L17) UART3_RXD */
-	{OFFSET(mii1_rxd2), (MODE(1) | PULLUDEN | PULLUP_EN | SLEWCTRL)},	/* (L16) UART3_TXD */
+	{OFFSET(mii1_rxd3), (MODE(1) | PULLUDDIS | RXACTIVE)},			/* (L17) UART3_RXD */
+	{OFFSET(mii1_rxd2), (MODE(1) | PULLUDDIS | SLEWCTRL)},			/* (L16) UART3_TXD */
 	{-1}
 };