diff --git a/src/date.cpp b/src/date.cpp
--- a/src/date.cpp
+++ b/src/date.cpp
@@ -23,7 +23,7 @@
 Year      _cur_year;   ///< Current year, starting at 0
 Month     _cur_month;  ///< Current month (0..11)
 Date      _date;       ///< Current date in days (day counter)
-DateFract _date_fract;
+DateFract _date_fract; ///< Fractional part of the day.
 uint16 _tick_counter;  ///< Ever incrementing (and sometimes wrapping) tick counter for setting off various events
 
 /**