diff --git a/registry/client/auth/authchallenge.go b/registry/client/auth/authchallenge.go
index a6ad45d8..c8cd83bb 100644
--- a/registry/client/auth/authchallenge.go
+++ b/registry/client/auth/authchallenge.go
@@ -25,7 +25,7 @@ type Challenge struct {
 type ChallengeManager interface {
 	// GetChallenges returns the challenges for the given
 	// endpoint URL.
-	GetChallenges(endpoint string) ([]Challenge, error)
+	GetChallenges(endpoint url.URL) ([]Challenge, error)
 
 	// AddResponse adds the response to the challenge
 	// manager. The challenges will be parsed out of
@@ -48,8 +48,10 @@ func NewSimpleChallengeManager() ChallengeManager {
 
 type simpleChallengeManager map[string][]Challenge
 
-func (m simpleChallengeManager) GetChallenges(endpoint string) ([]Challenge, error) {
-	challenges := m[endpoint]
+func (m simpleChallengeManager) GetChallenges(endpoint url.URL) ([]Challenge, error) {
+	endpoint.Host = strings.ToLower(endpoint.Host)
+
+	challenges := m[endpoint.String()]
 	return challenges, nil
 }
 
@@ -60,11 +62,10 @@ func (m simpleChallengeManager) AddResponse(resp *http.Response) error {
 	}
 	urlCopy := url.URL{
 		Path:   resp.Request.URL.Path,
-		Host:   resp.Request.URL.Host,
+		Host:   strings.ToLower(resp.Request.URL.Host),
 		Scheme: resp.Request.URL.Scheme,
 	}
 	m[urlCopy.String()] = challenges
-
 	return nil
 }
 
diff --git a/registry/client/auth/authchallenge_test.go b/registry/client/auth/authchallenge_test.go
index 9b6a5adc..953ed5b4 100644
--- a/registry/client/auth/authchallenge_test.go
+++ b/registry/client/auth/authchallenge_test.go
@@ -1,7 +1,10 @@
 package auth
 
 import (
+	"fmt"
 	"net/http"
+	"net/url"
+	"strings"
 	"testing"
 )
 
@@ -36,3 +39,43 @@ func TestAuthChallengeParse(t *testing.T) {
 	}
 
 }
+
+func TestAuthChallengeNormalization(t *testing.T) {
+	testAuthChallengeNormalization(t, "reg.EXAMPLE.com")
+	testAuthChallengeNormalization(t, "bɿɒʜɔiɿ-ɿɘƚƨim-ƚol-ɒ-ƨʞnɒʜƚ.com")
+}
+
+func testAuthChallengeNormalization(t *testing.T, host string) {
+
+	scm := NewSimpleChallengeManager()
+
+	url, err := url.Parse(fmt.Sprintf("http://%s/v2/", host))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	resp := &http.Response{
+		Request: &http.Request{
+			URL: url,
+		},
+		Header:     make(http.Header),
+		StatusCode: http.StatusUnauthorized,
+	}
+	resp.Header.Add("WWW-Authenticate", fmt.Sprintf("Bearer realm=\"https://%s/token\",service=\"registry.example.com\"", host))
+
+	err = scm.AddResponse(resp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	lowered := *url
+	lowered.Host = strings.ToLower(lowered.Host)
+	c, err := scm.GetChallenges(lowered)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(c) == 0 {
+		t.Fatal("Expected challenge for lower-cased-host URL")
+	}
+}
diff --git a/registry/client/auth/session.go b/registry/client/auth/session.go
index 058a87b9..c80108ac 100644
--- a/registry/client/auth/session.go
+++ b/registry/client/auth/session.go
@@ -77,9 +77,7 @@ func (ea *endpointAuthorizer) ModifyRequest(req *http.Request) error {
 		Path:   req.URL.Path[:v2Root+4],
 	}
 
-	pingEndpoint := ping.String()
-
-	challenges, err := ea.challenges.GetChallenges(pingEndpoint)
+	challenges, err := ea.challenges.GetChallenges(ping)
 	if err != nil {
 		return err
 	}
diff --git a/registry/handlers/blobupload.go b/registry/handlers/blobupload.go
index 892393aa..673e2c59 100644
--- a/registry/handlers/blobupload.go
+++ b/registry/handlers/blobupload.go
@@ -319,6 +319,7 @@ func (buh *blobUploadHandler) blobUploadResponse(w http.ResponseWriter, r *http.
 
 	w.Header().Set("Docker-Upload-UUID", buh.UUID)
 	w.Header().Set("Location", uploadURL)
+
 	w.Header().Set("Content-Length", "0")
 	w.Header().Set("Range", fmt.Sprintf("0-%d", endRange))
 
diff --git a/registry/proxy/proxyregistry.go b/registry/proxy/proxyregistry.go
index 1663ab69..56818dab 100644
--- a/registry/proxy/proxyregistry.go
+++ b/registry/proxy/proxyregistry.go
@@ -22,13 +22,13 @@ import (
 type proxyingRegistry struct {
 	embedded       distribution.Namespace // provides local registry functionality
 	scheduler      *scheduler.TTLExpirationScheduler
-	remoteURL      string
+	remoteURL      url.URL
 	authChallenger authChallenger
 }
 
 // NewRegistryPullThroughCache creates a registry acting as a pull through cache
 func NewRegistryPullThroughCache(ctx context.Context, registry distribution.Namespace, driver driver.StorageDriver, config configuration.Proxy) (distribution.Namespace, error) {
-	_, err := url.Parse(config.RemoteURL)
+	remoteURL, err := url.Parse(config.RemoteURL)
 	if err != nil {
 		return nil, err
 	}
@@ -99,9 +99,9 @@ func NewRegistryPullThroughCache(ctx context.Context, registry distribution.Name
 	return &proxyingRegistry{
 		embedded:  registry,
 		scheduler: s,
-		remoteURL: config.RemoteURL,
+		remoteURL: *remoteURL,
 		authChallenger: &remoteAuthChallenger{
-			remoteURL: config.RemoteURL,
+			remoteURL: *remoteURL,
 			cm:        auth.NewSimpleChallengeManager(),
 			cs:        cs,
 		},
@@ -131,7 +131,7 @@ func (pr *proxyingRegistry) Repository(ctx context.Context, name reference.Named
 		return nil, err
 	}
 
-	remoteRepo, err := client.NewRepository(ctx, name, pr.remoteURL, tr)
+	remoteRepo, err := client.NewRepository(ctx, name, pr.remoteURL.String(), tr)
 	if err != nil {
 		return nil, err
 	}
@@ -182,7 +182,7 @@ type authChallenger interface {
 }
 
 type remoteAuthChallenger struct {
-	remoteURL string
+	remoteURL url.URL
 	sync.Mutex
 	cm auth.ChallengeManager
 	cs auth.CredentialStore
@@ -201,8 +201,9 @@ func (r *remoteAuthChallenger) tryEstablishChallenges(ctx context.Context) error
 	r.Lock()
 	defer r.Unlock()
 
-	remoteURL := r.remoteURL + "/v2/"
-	challenges, err := r.cm.GetChallenges(remoteURL)
+	remoteURL := r.remoteURL
+	remoteURL.Path = "/v2/"
+	challenges, err := r.cm.GetChallenges(r.remoteURL)
 	if err != nil {
 		return err
 	}
@@ -212,7 +213,7 @@ func (r *remoteAuthChallenger) tryEstablishChallenges(ctx context.Context) error
 	}
 
 	// establish challenge type with upstream
-	if err := ping(r.cm, remoteURL, challengeHeader); err != nil {
+	if err := ping(r.cm, remoteURL.String(), challengeHeader); err != nil {
 		return err
 	}