passport renewal due in 6 months, H1 expires 5 months

[checkstats]

Hi,
Here is a situation and just trying to figure out of it is better to renew passport before applying for H-1B extension or it is better to renew passport of after getting decision on H-1B Extension which can go very long due to possible RFE..

example:
Passport expiring: May-15-2015
H-1B expiring: March-15-2015

I think renewing passport first is better, but Appreciate your suggestions, if you know one way is better than the other.

Thanks