Log Work: input validation or error/ warning message required

Minutes will be cut without a warning message, if you do not stick to the input format that is explained in the log work screen !!!

If the input value is '2h 30m' the work log records 2 hours and 30 minutes.
If, however, the input vaue is '2h30m' the work log records 2 hours only!

It is very important for our customer's project cost accounting that the figures for the "time spent" are accurate!
And it is unacceptable that an input value of the user is changed to another value without any error or warning
message because of a wrong syntax!!

Please advise!