diff --git a/arch/arm/src/stm32l4/Make.defs b/arch/arm/src/stm32l4/Make.defs
index c073ad1a2bd..bb164bfeacc 100644
--- a/arch/arm/src/stm32l4/Make.defs
+++ b/arch/arm/src/stm32l4/Make.defs
@@ -100,11 +100,15 @@ endif
 
 CHIP_ASRCS  =
 CHIP_CSRCS  = stm32l4_allocateheap.c stm32l4_exti_gpio.c stm32l4_gpio.c
-CHIP_CSRCS += stm32l4_idle.c stm32l4_irq.c stm32l4_lowputc.c stm32l4_rcc.c
+CHIP_CSRCS += stm32l4_irq.c stm32l4_lowputc.c stm32l4_rcc.c
 CHIP_CSRCS += stm32l4_serial.c stm32l4_start.c stm32l4_waste.c stm32l4_uid.c
 CHIP_CSRCS += stm32l4_spi.c stm32l4_i2c.c stm32l4_lse.c stm32l4_lsi.c
 CHIP_CSRCS += stm32l4_pwr.c stm32l4_tim.c stm32l4_flash.c
 
+ifneq ($(CONFIG_ARCH_IDLE_CUSTOM),y)
+CHIP_CSRCS += stm32l4_idle.c
+endif
+
 ifeq ($(CONFIG_TIMER),y)
 CHIP_CSRCS += stm32l4_tim_lowerhalf.c
 endif