diff --git a/csclient/csclient.go b/csclient/csclient.go
index 4ec73dd..6de8bf5 100644
--- a/csclient/csclient.go
+++ b/csclient/csclient.go
@@ -20,6 +20,7 @@ import (
 	"gopkg.in/errgo.v1"
 	"gopkg.in/juju/charm.v6-unstable"
 	"gopkg.in/macaroon-bakery.v1/httpbakery"
+	"gopkg.in/macaroon.v1"
 
 	"gopkg.in/juju/charmrepo.v2-unstable/csclient/params"
 )
@@ -73,6 +74,10 @@ type Params struct {
 	// If nil, no interaction will be allowed. This field
 	// is ignored if BakeryClient is provided.
 	VisitWebPage func(url *url.URL) error
+
+	// Auth holds a list of macaroons that will be added to the cookie jar of
+	// the HTTP Client that is used by this client.
+	Auth macaroon.Slice
 }
 
 type httpClient interface {
@@ -94,6 +99,15 @@ func New(p Params) *Client {
 			VisitWebPage: p.VisitWebPage,
 		}
 	}
+	if len(p.Auth) > 0 {
+		url, err := url.Parse(p.URL)
+		// A non-nil error here will get caught at request time when we try
+		// to parse the URL, and without a valid URL, the macaroons don't matter
+		// anyway.
+		if err == nil {
+			httpbakery.SetCookie(bclient.Jar, url, p.Auth)
+		}
+	}
 	return &Client{
 		bclient: bclient,
 		params:  p,
diff --git a/csclient/csclient_resources_test.go b/csclient/csclient_resources_test.go
index b796cd5..64f367c 100644
--- a/csclient/csclient_resources_test.go
+++ b/csclient/csclient_resources_test.go
@@ -9,6 +9,7 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"net/url"
 	"strings"
 
 	"github.com/juju/testing"
@@ -16,6 +17,8 @@ import (
 	gc "gopkg.in/check.v1"
 	"gopkg.in/juju/charm.v6-unstable"
 	"gopkg.in/juju/charm.v6-unstable/resource"
+	"gopkg.in/macaroon-bakery.v1/httpbakery"
+	"gopkg.in/macaroon.v1"
 
 	"gopkg.in/juju/charmrepo.v2-unstable/csclient/params"
 )
@@ -160,6 +163,26 @@ func (ResourceSuite) TestResourceMeta(c *gc.C) {
 	c.Assert(resdata, gc.DeepEquals, result)
 }
 
+type InternalSuite struct{}
+
+var _ = gc.Suite(InternalSuite{})
+
+func (s InternalSuite) TestMacaroon(c *gc.C) {
+	var m macaroon.Macaroon
+	macs := macaroon.Slice{&m}
+	client := New(Params{
+		URL:  "https://foo.com",
+		Auth: macs,
+	})
+	u, err := url.Parse("https://foo.com")
+	c.Assert(err, jc.ErrorIsNil)
+	bc := client.bclient.(*httpbakery.Client)
+	cookies := bc.Jar.Cookies(u)
+	expected, err := httpbakery.NewCookie(macs)
+	c.Assert(err, jc.ErrorIsNil)
+	c.Assert(cookies, gc.DeepEquals, []*http.Cookie{expected})
+}
+
 type fakeClient struct {
 	*testing.Stub
 	ReturnDoWithBody *http.Response