Is there a way to make a sumifs formula that still works if one of the criteria is blank in some cases.

=SUMIFS('Indirect Rate Plan Analysis'!$F:$F,'Indirect Rate Plan Analysis'!$D:$D,$D17,'Indirect Rate Plan Analysis'!$L:$L,$C17,'Indirect Rate Plan Analysis'!$G:$G,E$15)

Sometimes C17 is blank

Thanks