diff --git a/cmds/signin/signin.go b/cmds/signin/signin.go
index 4b9faf2..c906977 100644
--- a/cmds/signin/signin.go
+++ b/cmds/signin/signin.go
@@ -18,6 +18,7 @@ import (
 	"github.com/taskcluster/taskcluster-cli/config"
 	tcclient "github.com/taskcluster/taskcluster-client-go"
 	"github.com/taskcluster/taskcluster-client-go/auth"
+	libUrls "github.com/taskcluster/taskcluster-lib-urls"
 	graceful "gopkg.in/tylerb/graceful.v1"
 )
 
@@ -52,9 +53,10 @@ tools using those libraries can also benefit from this signin method.`,
 	root.Command.AddCommand(cmd)
 
 	config.RegisterOptions("signin", map[string]config.OptionDefinition{
-		"toolsUrl": config.OptionDefinition{
-			Description: "URL for the tools service.",
-			Default:     "https://tools.taskcluster.net",
+		"rootUrl": config.OptionDefinition{
+			Description: "Root URL against which to act",
+			Default:     "https://taskcluster.net",
+			Env:         "TASKCLUSTER_ROOT_URL",
 			Validate: func(value interface{}) error {
 				if _, ok := value.(string); !ok {
 					return errors.New("Must be a string")
@@ -87,12 +89,15 @@ func cmdSignin(cmd *cobra.Command, _ []string) error {
 	s.Server.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		qs := r.URL.Query()
 		csh, _ := cmd.Flags().GetBool("csh")
+		rootURL := config.Configuration["signin"]["rootUrl"].(string)
 		if csh {
 			fmt.Fprintln(cmd.OutOrStdout(), "setenv TASKCLUSTER_CLIENT_ID '"+qs.Get("clientId")+"'")
 			fmt.Fprintln(cmd.OutOrStdout(), "setenv TASKCLUSTER_ACCESS_TOKEN '"+qs.Get("accessToken")+"'")
+			fmt.Fprintln(cmd.OutOrStdout(), "setenv TASKCLUSTER_ROOT_URL '"+rootURL+"'")
 		} else {
 			fmt.Fprintln(cmd.OutOrStdout(), "export TASKCLUSTER_CLIENT_ID='"+qs.Get("clientId")+"'")
 			fmt.Fprintln(cmd.OutOrStdout(), "export TASKCLUSTER_ACCESS_TOKEN='"+qs.Get("accessToken")+"'")
+			fmt.Fprintln(cmd.OutOrStdout(), "export TASKCLUSTER_ROOT_URL='"+rootURL+"'")
 		}
 		fmt.Fprintln(cmd.OutOrStderr(), "Credentials output as environment variables")
 
@@ -124,7 +129,7 @@ func cmdSignin(cmd *cobra.Command, _ []string) error {
 	// Construct URL for login service and open it
 	callbackURL := "http://" + strings.Replace(listener.Addr().String(), "127.0.0.1", "localhost", 1)
 	description := url.QueryEscape("Temporary client for use on the command line")
-	loginURL := config.Configuration["signin"]["toolsUrl"].(string) + "/auth/clients/new"
+	loginURL := libUrls.UI(config.Configuration["signin"]["rootUrl"].(string), "/auth/clients/new")
 	name, _ := cmd.Flags().GetString("name")
 	loginURL += "?name=" + url.QueryEscape(name)
 	loginURL += "&description=" + description
diff --git a/vendor/vendor.json b/vendor/vendor.json
index 52f3c4c..fdf2284 100644
--- a/vendor/vendor.json
+++ b/vendor/vendor.json
@@ -149,7 +149,7 @@
 			"revisionTime": "2017-03-30T08:48:43Z"
 		},
 		{
-			"checksumSHA1": "GPl+4G/6LSTGEgPtxqlIQhXJ82U=",
+			"checksumSHA1": "DCjamhJdcLN963jm6/yFoDbJvT4=",
 			"path": "github.com/shirou/gopsutil/disk",
 			"revision": "e49a95f3d5f824c3f9875ca49e54e4fef17f82cf",
 			"revisionTime": "2017-04-06T13:17:56Z"
@@ -161,7 +161,7 @@
 			"revisionTime": "2017-04-06T13:17:56Z"
 		},
 		{
-			"checksumSHA1": "rLo31ffS0VeaRYKDTm+WSd8nUQ4=",
+			"checksumSHA1": "zkNNauN735M7Jghr+MsARbb+/xQ=",
 			"path": "github.com/shirou/gopsutil/mem",
 			"revision": "e49a95f3d5f824c3f9875ca49e54e4fef17f82cf",
 			"revisionTime": "2017-04-06T13:17:56Z"
@@ -286,6 +286,12 @@
 			"revision": "d0979b7bd0a8f9c555b9ffca20e95dbf02f0cfce",
 			"revisionTime": "2017-04-07T13:25:32Z"
 		},
+		{
+			"checksumSHA1": "RRxFQSmAKEqOr0yNyocMTnVfZEo=",
+			"path": "github.com/taskcluster/taskcluster-lib-urls",
+			"revision": "fa4efabda5891c53b4885970852eb0d5c487d977",
+			"revisionTime": "2018-06-01T19:41:51Z"
+		},
 		{
 			"checksumSHA1": "Es6jQ7nOtzvM74kkdt1BTj2CvBY=",
 			"path": "github.com/taskcluster/taskcluster-worker/engines",
@@ -383,7 +389,7 @@
 			"revisionTime": "2016-12-29T22:47:41Z"
 		},
 		{
-			"checksumSHA1": "oBjdFvDUZpioGsB6URqe16hDQUg=",
+			"checksumSHA1": "aQcK6fcqVIdpOQ7Gw6qkFiDtnrE=",
 			"origin": "github.com/fatih/color/vendor/golang.org/x/sys/unix",
 			"path": "golang.org/x/sys/unix",
 			"revision": "9131ab34cf20d2f6d83fdc67168a5430d1c7dc23",