undefined: atomic.SwapInt32

[NTBTI]

Getting this as an error when running make

godep go build -o bin/go-mysql-elasticsearch ./cmd/go-mysql-elasticsearch

github.com/siddontang/go/sync2

Godeps/_workspace/src/github.com/siddontang/go/sync2/semaphore.go:48: undefined: atomic.SwapInt32
Godeps/_workspace/src/github.com/siddontang/go/sync2/semaphore.go:59: undefined: atomic.SwapInt32
godep: go exit status 2
make: *** [build-elasticsearch] Error 1

Have never used GO before so not sure how I go about fixing it

go1.1.1 linux/amd64

[NTBTI]

Fixed it....upgraded to go1.4.1