diff --git a/drivers/watchdog/wdt_iwdg_stm32.c b/drivers/watchdog/wdt_iwdg_stm32.c
index b0cff3b2bb0..cb52cc49b7f 100644
--- a/drivers/watchdog/wdt_iwdg_stm32.c
+++ b/drivers/watchdog/wdt_iwdg_stm32.c
@@ -151,7 +151,7 @@ static int iwdg_stm32_init(struct device *dev)
 #ifdef CONFIG_IWDG_STM32_START_AT_BOOT
 	IWDG_TypeDef *iwdg = IWDG_STM32_STRUCT(dev);
 	struct wdt_timeout_cfg config = {
-		.window.max = CONFIG_IWDG_STM32_TIMEOUT * USEC_PER_MSEC,
+		.window.max = CONFIG_IWDG_STM32_TIMEOUT / USEC_PER_MSEC,
 	};
 
 	LL_IWDG_Enable(iwdg);