FCFF from CFAI text first, increase, interest, several

pacmandefense

Was looking at the end of topic questions for Free Cash Flow and the first Q asks for the effect on FCFF and FCFE for an increase of 100 on several NI and BS items. Assume 40% tax.
for an increase in interest expense of 100 it says it has NO effect on FCFF and -60 for FCFE which is clear.
shouldnt interest expense increase FCFF????