diff --git a/libraries/RTC/src/RTC.cpp b/libraries/RTC/src/RTC.cpp
index 02946e9..410c1aa 100644
--- a/libraries/RTC/src/RTC.cpp
+++ b/libraries/RTC/src/RTC.cpp
@@ -59,7 +59,7 @@ void APM3_RTC::setTime(uint8_t hour, uint8_t min, uint8_t sec, uint8_t hund, uin
   hal_time.ui32Year = year;
   hal_time.ui32Century = 0;
 
-  hal_time.ui32Weekday = am_util_time_computeDayofWeek(2000 + year, month + 1, dayOfMonth);
+  hal_time.ui32Weekday = am_util_time_computeDayofWeek(2000 + year, month, dayOfMonth); //computeDayofWeek is expecting 1 to 12 months
 
   am_hal_rtc_time_set(&hal_time); //Initialize the RTC with this date/time
 }