@@ -9,6 +9,7 @@ package parser

 import (

 	"encoding/json"

 	"errors"

+	"fmt"

 	"strconv"

 	"strings"

 )

@@ -43,6 +44,11 @@ func parseEnv(rest string) (*Node, map[string]bool, error) {

 	node := &Node{}

 	rootnode := node

 	strs := TOKEN_WHITESPACE.Split(rest, 2)

+

+	if len(strs) < 2 {

+		return nil, nil, fmt.Errorf("ENV must have two arguments")

+	}

+

 	node.Value = strs[0]

 	node.Next = &Node{}

 	node.Next.Value = strs[1]

new file mode 100644

@@ -0,0 +1,3 @@

+FROM busybox

+

+ENV PATH=PATH