diff --git a/firmware/config/stm32f4ems/mcuconf.h b/firmware/config/stm32f4ems/mcuconf.h
index 300751e786..b79c414184 100644
--- a/firmware/config/stm32f4ems/mcuconf.h
+++ b/firmware/config/stm32f4ems/mcuconf.h
@@ -20,7 +20,15 @@
 #include "efifeatures.h"
 #include "rusefi_enums.h"
 
-#define SCHEDULING_TIMER_PRIORITY 4
+/**
+ * This is about SingleTimerExecutor - rusEfi 1MHz precise scheduling timer
+ * this is not about ChibiOS virtual timer which rusEfi uses for
+ * periodicFastCallback and periodicSlowCallback
+ */
+#define PRECISE_SCHEDULING_TIMER_PRIORITY 4
+/**
+ * Input Capture Unit is how we capture shaft position sensors output
+ */
 #define ICU_PRIORITY 3
 
 /*
@@ -150,7 +158,7 @@
 #define STM32_GPT_TIM2_IRQ_PRIORITY         7
 #define STM32_GPT_TIM3_IRQ_PRIORITY         7
 #define STM32_GPT_TIM4_IRQ_PRIORITY         7
-#define STM32_GPT_TIM5_IRQ_PRIORITY         SCHEDULING_TIMER_PRIORITY
+#define STM32_GPT_TIM5_IRQ_PRIORITY         PRECISE_SCHEDULING_TIMER_PRIORITY
 #define STM32_GPT_TIM6_IRQ_PRIORITY         7
 #define STM32_GPT_TIM7_IRQ_PRIORITY         7
 #define STM32_GPT_TIM8_IRQ_PRIORITY         7