lego: Receiving a panic runtime error when attempting to renew after expiration

user@machine:~/utils/lego$ sudo ./lego --domains="<existing domain>" --email="<existing email address>" renew
2016/04/14 17:23:15 [INFO][<existing domain>] acme: Trying renewal with -42 hours remaining
2016/04/14 17:23:15 [INFO][<existing domain>] acme: Obtaining bundled SAN certificate
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x4a45e9]

goroutine 16 [running]:
panic(0x95f440, 0xc8200100e0)
        /usr/local/go/src/runtime/panic.go:464 +0x3e6
github.com/xenolf/lego/acme.(*Client).getChallenges.func1(0xc820102090, 0xc82023acc0, 0xc82023ac60, 0xc8203f53a0, 0x14)
        /home/azhwkd/Projects/go/src/github.com/xenolf/lego/acme/client.go:408 +0x5c9
created by github.com/xenolf/lego/acme.(*Client).getChallenges
        /home/azhwkd/Projects/go/src/github.com/xenolf/lego/acme/client.go:421 +0x17c

If there’s any other info I need to provide, please let me know!