Docker build error

Am I doing something wrong here? On macOS Sierra. Docke

```
adysan@adyNUC:~$ cd git
adysan@adyNUC:~/git$ git clone https://github.com/evilsocket/dnssearch.git
Cloning into 'dnssearch'...
remote: Counting objects: 22, done.
remote: Compressing objects: 100% (16/16), done.
remote: Total 22 (delta 8), reused 19 (delta 5), pack-reused 0
Unpacking objects: 100% (22/22), done.
Checking connectivity... done.
adysan@adyNUC:~/git$ cd dnssearch/
adysan@adyNUC:~/git/dnssearch$ docker build -t dnssearch .
Sending build context to Docker daemon 2.786 MB
Step 1/9 : FROM golang:1.8 as build-stage
Error parsing reference: "golang:1.8 as build-stage" is not a valid repository/tag: invalid reference format
adysan@adyNUC:~/git/dnssearch$ docker -v
Docker version 17.03.1-ce, build c6d412e
```