diff --git a/drivers/pinmux/stm32/pinmux_stm32h7.h b/drivers/pinmux/stm32/pinmux_stm32h7.h
index 9947eef66a0..1f72fbe0fef 100644
--- a/drivers/pinmux/stm32/pinmux_stm32h7.h
+++ b/drivers/pinmux/stm32/pinmux_stm32h7.h
@@ -53,7 +53,7 @@
 #define STM32H7_PINMUX_FUNC_PB6_USART1_TX   \
 	(STM32_PINMUX_ALT_FUNC_7 | STM32_PUSHPULL_PULLUP)
 #define STM32H7_PINMUX_FUNC_PB6_LPUART1_TX    \
-	(STM32_PINMUX_ALT_FUNC_6 | STM32_OPENDRAIN_PULLUP)
+	(STM32_PINMUX_ALT_FUNC_8 | STM32_OPENDRAIN_PULLUP)
 
 #define STM32H7_PINMUX_FUNC_PB7_USART1_RX   \
 	(STM32_PINMUX_ALT_FUNC_7 | STM32_PUSHPULL_NOPULL)