diff --git a/os_port.c b/os_port.c
index 773be45..f9631a8 100644
--- a/os_port.c
+++ b/os_port.c
@@ -92,8 +92,8 @@ void os_port_init(void){
 }
 
 void os_port_startup(void){
+    NVIC_SetPriority(SVCall_IRQn, 0x00);
     NVIC_SetPriority(PendSV_IRQn, 0xff);
-    NVIC_SetPriority(SVCall_IRQn, OS_CFG_SYSCALL_PRIORITY);
     SysTick_Config(SystemCoreClock/OS_CFG_TICKS_PER_SECOND);
 }