Need help with a formula

Im building an employee data sheet and one of the columns is HIRE DATE, the next column is 90 DAY REVIEW DATE. Both columns are date formatted. The formula in the 90 DAY REVIEW DATE cells is simply the hire date + 90. The problem is that if there is not a date in the hire date cell, the date that is being displayed in the 90 DAY REVIEW DATE is 3/30/1900, (I assume this is the default beginning date in Excel?)  I do not want anything displayed in the 90 DATE REVIEW DATE column is there is not a date in the HIRE DATE column. Can someone help me with this please?