@@ -34,6 +34,9 @@ func NewDiffCommand(dockerCli *client.DockerCli) *cobra.Command {

 }

 func runDiff(dockerCli *client.DockerCli, opts *diffOptions) error {

+	if opts.container == "" {

+		return fmt.Errorf("Container name cannot be empty")

+	}

 	ctx := context.Background()

 	changes, err := dockerCli.Client().ContainerDiff(ctx, opts.container)

@@ -83,5 +83,5 @@ func (s *DockerSuite) TestDiffEnsureDefaultDevs(c *check.C) {

 func (s *DockerSuite) TestDiffEmptyArgClientError(c *check.C) {

 	out, _, err := dockerCmdWithError("diff", "")

 	c.Assert(err, checker.NotNil)

-	c.Assert(strings.TrimSpace(out), checker.Contains, "\"docker diff\" requires exactly 1 argument(s).")

+	c.Assert(strings.TrimSpace(out), checker.Contains, "Container name cannot be empty")

 }