diff --git a/radio/src/rtos.h b/radio/src/rtos.h
index 6e42ebf30..98d0c0415 100644
--- a/radio/src/rtos.h
+++ b/radio/src/rtos.h
@@ -155,7 +155,7 @@ template<int SIZE>
   }
 #endif
 
-  #define RTOS_MS_PER_TICK              ((CFG_CPU_FREQ / CFG_SYSTICK_FREQ) / (CFG_CPU_FREQ / 1000))  // RTOS timer tick length in ms (currently 2)
+  #define RTOS_MS_PER_TICK              (1000 / CFG_SYSTICK_FREQ)  // RTOS timer tick length in ms (currently 1 for STM32, 2 for others)
 
   typedef OS_TID RTOS_TASK_HANDLE;
   typedef OS_MutexID RTOS_MUTEX_HANDLE;