void SysTick_Handler (void) { #if (configUSE_TICKLESS_IDLE == 0) /* Clear overflow flag */ SysTick->CTRL; #endif and as a consequence also osKernelGetSysTimerCount had to be updated: CMSIS-FreeRTOS/CMSIS/RTOS2/FreeRTOS/Source/cmsis_os2.c Lines 475 to 516 in 13acfbe ...