@@ -21,7 +21,6 @@ package dockerfile

 import (

 	"fmt"

-	"runtime"

 	"strings"

 	"github.com/docker/docker/builder/dockerfile/command"

@@ -200,16 +199,3 @@ func (b *Builder) dispatch(stepN int, ast *parser.Node) error {

 	return fmt.Errorf("Unknown instruction: %s", upperCasedCmd)

 }

-

-// platformSupports is a short-term function to give users a quality error

-// message if a Dockerfile uses a command not supported on the platform.

-func platformSupports(command string) error {

-	if runtime.GOOS != "windows" {

-		return nil

-	}

-	switch command {

-	case "expose", "user", "stopsignal", "arg":

-		return fmt.Errorf("The daemon on this platform does not support the command '%s'", command)

-	}

-	return nil

-}

new file mode 100644

@@ -0,0 +1,9 @@

+// +build !windows

+

+package dockerfile

+

+// platformSupports is a short-term function to give users a quality error

+// message if a Dockerfile uses a command not supported on the platform.

+func platformSupports(command string) error {

+	return nil

+}

new file mode 100644

@@ -0,0 +1,26 @@

+// +build windows

+

+package dockerfile

+

+import (

+	"fmt"

+

+	"github.com/Microsoft/hcsshim"

+)

+

+// platformSupports is a short-term function to give users a quality error

+// message if a Dockerfile uses a command not supported on the platform.

+func platformSupports(command string) error {

+	switch command {

+	// TODO Windows TP5. Expose can be removed from here once TP4 is

+	// no longer supported.

+	case "expose":

+		if !hcsshim.IsTP4() {

+			break

+		}

+		fallthrough

+	case "user", "stopsignal", "arg":

+		return fmt.Errorf("The daemon on this platform does not support the command '%s'", command)

+	}

+	return nil

+}