diff --git a/drivers/timer/stm32_lptim_timer.c b/drivers/timer/stm32_lptim_timer.c
index b9c255e3e0c..e2a14d65d61 100644
--- a/drivers/timer/stm32_lptim_timer.c
+++ b/drivers/timer/stm32_lptim_timer.c
@@ -28,6 +28,7 @@
 #define LPTIM (LPTIM_TypeDef *) DT_INST_REG_ADDR(0)
 
 #if DT_INST_NUM_CLOCKS(0) == 1
+#warning Kconfig for LPTIM source clock (LSI/LSE) is deprecated, use device tree.
 static const struct stm32_pclken lptim_clk[] = {
 	STM32_CLOCK_INFO(0, DT_DRV_INST(0)),
 	/* Use Kconfig to configure source clocks fields */