diff --git a/runsc/boot/controller.go b/runsc/boot/controller.go
index 7d7803e92..bc33e028a 100644
--- a/runsc/boot/controller.go
+++ b/runsc/boot/controller.go
@@ -171,7 +171,6 @@ func (cm *containerManager) StartRoot(cid *string, _ *struct{}) error {
 	if err := <-cm.startResultChan; err != nil {
 		return fmt.Errorf("failed to start sandbox: %v", err)
 	}
-	cm.l.setRootContainerID(*cid)
 	return nil
 }
 
diff --git a/runsc/boot/loader.go b/runsc/boot/loader.go
index 5867eec96..9a5d649ab 100644
--- a/runsc/boot/loader.go
+++ b/runsc/boot/loader.go
@@ -142,7 +142,7 @@ func init() {
 
 // New initializes a new kernel loader configured by spec.
 // New also handles setting up a kernel for restoring a container.
-func New(spec *specs.Spec, conf *Config, controllerFD, deviceFD int, goferFDs []int, console bool) (*Loader, error) {
+func New(id string, spec *specs.Spec, conf *Config, controllerFD, deviceFD int, goferFDs []int, console bool) (*Loader, error) {
 	if err := usage.Init(); err != nil {
 		return nil, fmt.Errorf("Error setting up memory usage: %v", err)
 	}
@@ -286,6 +286,9 @@ func New(spec *specs.Spec, conf *Config, controllerFD, deviceFD int, goferFDs []
 		spec:                  spec,
 		startSignalForwarding: startSignalForwarding,
 		rootProcArgs:          procArgs,
+		sandboxID:             id,
+		containerRootTGs:      make(map[string]*kernel.ThreadGroup),
+		execProcesses:         make(map[execID]*kernel.ThreadGroup),
 	}
 	ctrl.manager.l = l
 	return l, nil
@@ -420,10 +423,9 @@ func (l *Loader) run() error {
 		l.rootProcArgs.FDMap.DecRef()
 	}
 
-	if l.execProcesses != nil {
-		return fmt.Errorf("there shouldn't already be a cache of exec'd processes, but found: %v", l.execProcesses)
-	}
-	l.execProcesses = make(map[execID]*kernel.ThreadGroup)
+	l.mu.Lock()
+	l.containerRootTGs[l.sandboxID] = l.k.GlobalInit()
+	l.mu.Unlock()
 
 	// Start signal forwarding only after an init process is created.
 	l.stopSignalForwarding = l.startSignalForwarding()
diff --git a/runsc/boot/loader_test.go b/runsc/boot/loader_test.go
index a8a796445..0b363253d 100644
--- a/runsc/boot/loader_test.go
+++ b/runsc/boot/loader_test.go
@@ -101,7 +101,7 @@ func createLoader() (*Loader, func(), error) {
 		return nil, nil, err
 	}
 
-	l, err := New(spec, conf, fd, -1 /* device fd */, []int{sandEnd}, false)
+	l, err := New("foo", spec, conf, fd, -1 /* device fd */, []int{sandEnd}, false)
 	if err != nil {
 		cleanup()
 		return nil, nil, err
@@ -129,7 +129,6 @@ func TestRun(t *testing.T) {
 	}()
 
 	// Run the container.
-	l.setRootContainerID("foo")
 	if err := l.Run(); err != nil {
 		t.Errorf("error running container: %v", err)
 	}
diff --git a/runsc/cmd/boot.go b/runsc/cmd/boot.go
index 035147cf1..933ba2d9e 100644
--- a/runsc/cmd/boot.go
+++ b/runsc/cmd/boot.go
@@ -69,7 +69,7 @@ func (*Boot) Synopsis() string {
 
 // Usage implements subcommands.Command.Usage.
 func (*Boot) Usage() string {
-	return `boot [flags]`
+	return `boot [flags] <container id>`
 }
 
 // SetFlags implements subcommands.Command.SetFlags.
@@ -86,7 +86,7 @@ func (b *Boot) SetFlags(f *flag.FlagSet) {
 // Execute implements subcommands.Command.Execute.  It starts a sandbox in a
 // waiting state.
 func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
-	if b.specFD == -1 || b.controllerFD == -1 || f.NArg() != 0 {
+	if b.specFD == -1 || b.controllerFD == -1 || f.NArg() != 1 {
 		f.Usage()
 		return subcommands.ExitUsageError
 	}
@@ -138,7 +138,7 @@ func (b *Boot) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 	}
 
 	// Create the loader.
-	l, err := boot.New(spec, conf, b.controllerFD, b.deviceFD, b.ioFDs.GetArray(), b.console)
+	l, err := boot.New(f.Arg(0), spec, conf, b.controllerFD, b.deviceFD, b.ioFDs.GetArray(), b.console)
 	if err != nil {
 		Fatalf("error creating loader: %v", err)
 	}
diff --git a/runsc/sandbox/sandbox.go b/runsc/sandbox/sandbox.go
index 67244c725..c3d90d5f4 100644
--- a/runsc/sandbox/sandbox.go
+++ b/runsc/sandbox/sandbox.go
@@ -460,6 +460,9 @@ func (s *Sandbox) createSandboxProcess(spec *specs.Spec, conf *boot.Config, bund
 		}
 	}
 
+	// Add container as the last argument.
+	cmd.Args = append(cmd.Args, s.ID)
+
 	// Log the fds we are donating to the sandbox process.
 	for i, f := range cmd.ExtraFiles {
 		log.Debugf("Donating FD %d: %q", i+3, f.Name())