You can't claim that loss but it is added into cost basis of your next purchase.
If you hold your next buy, you can't claim it until you sell. If you ends up not holding anything, just forget about it and report as usual. All transactions need to be closed in the same year.
buy 100, sale 50 1/1/2011 --> wash sale loss, disallowed
buy 100 1/5/2011 sale 50 1/6/2011 --> normal loss allowed, basis is 150!
buy 100 3/5/2011 sale 500 12/3/2011 --> normal gain, basis is 100.
so your total gain is -0 -100 +400 = 300
It is same as -50 -50 +400 = 300.
