diff --git a/client.go b/client.go
index d4ef83684..ab75b567c 100644
--- a/client.go
+++ b/client.go
@@ -625,6 +625,11 @@ func (c *Client) SnapshotService(snapshotterName string) snapshots.Snapshotter {
 	return snproxy.NewSnapshotter(snapshotsapi.NewSnapshotsClient(c.conn), snapshotterName)
 }
 
+// DefaultNamespace return the default namespace
+func (c *Client) DefaultNamespace() string {
+	return c.defaultns
+}
+
 // TaskService returns the underlying TasksClient
 func (c *Client) TaskService() tasks.TasksClient {
 	if c.taskService != nil {
diff --git a/container_opts.go b/container_opts.go
index 76a9b9616..cf41d1aab 100644
--- a/container_opts.go
+++ b/container_opts.go
@@ -26,6 +26,7 @@ import (
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
+	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/oci"
 	"github.com/containerd/containerd/protobuf"
 	"github.com/containerd/containerd/snapshots"
@@ -307,6 +308,9 @@ func WithContainerExtension(name string, extension interface{}) NewContainerOpts
 // WithNewSpec generates a new spec for a new container
 func WithNewSpec(opts ...oci.SpecOpts) NewContainerOpts {
 	return func(ctx context.Context, client *Client, c *containers.Container) error {
+		if _, ok := namespaces.Namespace(ctx); !ok {
+			ctx = namespaces.WithNamespace(ctx, client.DefaultNamespace())
+		}
 		s, err := oci.GenerateSpec(ctx, client, c, opts...)
 		if err != nil {
 			return err