diff --git a/builder/builder.go b/builder/builder.go
index e655f9da60..685f27b061 100644
--- a/builder/builder.go
+++ b/builder/builder.go
@@ -10,7 +10,6 @@ func NewBuilder(opts *BuildOpts) *BuildFile {
 		Dockerfile:    nil,
 		Config:        &runconfig.Config{},
 		Options:       opts,
-		TmpContainers: UniqueMap{},
-		TmpImages:     UniqueMap{},
+		TmpContainers: map[string]struct{}{},
 	}
 }
diff --git a/builder/evaluator.go b/builder/evaluator.go
index 01805f892d..ec8edc98c8 100644
--- a/builder/evaluator.go
+++ b/builder/evaluator.go
@@ -38,8 +38,6 @@ import (
 	"github.com/docker/docker/utils"
 )
 
-type UniqueMap map[string]struct{}
-
 var (
 	ErrDockerfileEmpty = errors.New("Dockerfile cannot be empty")
 )
@@ -74,8 +72,7 @@ type BuildFile struct {
 	Options    *BuildOpts        // see below
 
 	// both of these are controlled by the Remove and ForceRemove options in BuildOpts
-	TmpContainers UniqueMap // a map of containers used for removes
-	TmpImages     UniqueMap // a map of images used for removes
+	TmpContainers map[string]struct{} // a map of containers used for removes
 
 	image       string         // image name for commit processing
 	maintainer  string         // maintainer name. could probably be removed.
@@ -147,13 +144,13 @@ func (b *BuildFile) Run(context io.Reader) (string, error) {
 	for i, n := range b.Dockerfile.Children {
 		if err := b.dispatch(i, n); err != nil {
 			if b.Options.ForceRemove {
-				b.clearTmp(b.TmpContainers)
+				b.clearTmp()
 			}
 			return "", err
 		}
 		fmt.Fprintf(b.Options.OutStream, " ---> %s\n", utils.TruncateID(b.image))
 		if b.Options.Remove {
-			b.clearTmp(b.TmpContainers)
+			b.clearTmp()
 		}
 	}
 
@@ -206,5 +203,7 @@ func (b *BuildFile) dispatch(stepN int, ast *parser.Node) error {
 		return f(b, strs, attrs)
 	}
 
+	fmt.Fprintf(b.Options.ErrStream, "# Skipping unknown instruction %s\n", strings.ToUpper(cmd))
+
 	return nil
 }
diff --git a/builder/internals.go b/builder/internals.go
index b1d5b21f03..51b2b63ab9 100644
--- a/builder/internals.go
+++ b/builder/internals.go
@@ -97,7 +97,6 @@ func (b *BuildFile) commit(id string, autoCmd []string, comment string) error {
 	if err != nil {
 		return err
 	}
-	b.TmpImages[image.ID] = struct{}{}
 	b.image = image.ID
 	return nil
 }
@@ -304,7 +303,7 @@ func (b *BuildFile) processImageFrom(img *imagepkg.Image) error {
 		b.Config = img.Config
 	}
 
-	if b.Config.Env == nil || len(b.Config.Env) == 0 {
+	if len(b.Config.Env) == 0 {
 		b.Config.Env = append(b.Config.Env, "PATH="+daemon.DefaultPathEnv)
 	}
 
@@ -549,13 +548,13 @@ func fixPermissions(destination string, uid, gid int) error {
 	})
 }
 
-func (b *BuildFile) clearTmp(containers map[string]struct{}) {
-	for c := range containers {
+func (b *BuildFile) clearTmp() {
+	for c := range b.TmpContainers {
 		tmp := b.Options.Daemon.Get(c)
 		if err := b.Options.Daemon.Destroy(tmp); err != nil {
 			fmt.Fprintf(b.Options.OutStream, "Error removing intermediate container %s: %s\n", utils.TruncateID(c), err.Error())
 		} else {
-			delete(containers, c)
+			delete(b.TmpContainers, c)
 			fmt.Fprintf(b.Options.OutStream, "Removing intermediate container %s\n", utils.TruncateID(c))
 		}
 	}
diff --git a/builder/parser/line_parsers.go b/builder/parser/line_parsers.go
index 999d97603d..93fa23ee85 100644
--- a/builder/parser/line_parsers.go
+++ b/builder/parser/line_parsers.go
@@ -116,18 +116,16 @@ func parseJSON(rest string) (*Node, map[string]bool, error) {
 func parseMaybeJSON(rest string) (*Node, map[string]bool, error) {
 	rest = strings.TrimSpace(rest)
 
-	if strings.HasPrefix(rest, "[") {
-		node, attrs, err := parseJSON(rest)
+	node, attrs, err := parseJSON(rest)
 
-		if err == nil {
-			return node, attrs, nil
-		}
-		if err == errDockerfileJSONNesting {
-			return nil, nil, err
-		}
+	if err == nil {
+		return node, attrs, nil
+	}
+	if err == errDockerfileJSONNesting {
+		return nil, nil, err
 	}
 
-	node := &Node{}
+	node = &Node{}
 	node.Value = rest
 	return node, nil, nil
 }
diff --git a/builder/parser/parser.go b/builder/parser/parser.go
index 47ffc9a678..8315412bd7 100644
--- a/builder/parser/parser.go
+++ b/builder/parser/parser.go
@@ -100,8 +100,7 @@ func Parse(rwc io.Reader) (*Node, error) {
 		}
 
 		if line != "" && child == nil {
-			for {
-				scanner.Scan()
+			for scanner.Scan() {
 				newline := strings.TrimSpace(scanner.Text())
 
 				if newline == "" {
diff --git a/builder/support.go b/builder/support.go
index 08cfa8defa..bae97e370f 100644
--- a/builder/support.go
+++ b/builder/support.go
@@ -19,6 +19,7 @@ func (b *BuildFile) replaceEnv(str string) string {
 			tmp := strings.SplitN(keyval, "=", 2)
 			if tmp[0] == matchKey {
 				str = strings.Replace(str, match, tmp[1], -1)
+				break
 			}
 		}
 	}
@@ -26,16 +27,6 @@ func (b *BuildFile) replaceEnv(str string) string {
 	return str
 }
 
-func (b *BuildFile) FindEnvKey(key string) int {
-	for k, envVar := range b.Config.Env {
-		envParts := strings.SplitN(envVar, "=", 2)
-		if key == envParts[0] {
-			return k
-		}
-	}
-	return -1
-}
-
 func handleJsonArgs(args []string, attributes map[string]bool) []string {
 	if attributes != nil && attributes["json"] {
 		return args