diff --git a/registry/registry.go b/registry/registry.go
index c51df1ac2d..683a64ab6a 100644
--- a/registry/registry.go
+++ b/registry/registry.go
@@ -119,9 +119,15 @@ func (r *Registry) setUserAgent(req *http.Request, extra ...VersionChecker) {
 	userAgent := make(map[string]string, len(r.baseVersions)+len(extra))
 
 	for _, v := range r.baseVersions {
+		if v == nil {
+			continue
+		}
 		userAgent[v.Name()] = v.Version()
 	}
 	for _, v := range extra {
+		if v == nil {
+			continue
+		}
 		userAgent[v.Name()] = v.Version()
 	}
 
@@ -188,7 +194,7 @@ func (r *Registry) GetRemoteImageJSON(imgID, registry string, token []string) ([
 		return nil, -1, fmt.Errorf("Failed to download json: %s", err)
 	}
 	req.Header.Set("Authorization", "Token "+strings.Join(token, ", "))
-	r.setUserAgent(req, nil)
+	r.setUserAgent(req)
 	res, err := r.client.Do(req)
 	if err != nil {
 		return nil, -1, fmt.Errorf("Failed to download json: %s", err)
@@ -216,7 +222,7 @@ func (r *Registry) GetRemoteImageLayer(imgID, registry string, token []string) (
 		return nil, fmt.Errorf("Error while getting from the server: %s\n", err)
 	}
 	req.Header.Set("Authorization", "Token "+strings.Join(token, ", "))
-	r.setUserAgent(req, nil)
+	r.setUserAgent(req)
 	res, err := r.client.Do(req)
 	if err != nil {
 		return nil, err
@@ -237,7 +243,7 @@ func (r *Registry) GetRemoteTags(registries []string, repository string, token [
 			return nil, err
 		}
 		req.Header.Set("Authorization", "Token "+strings.Join(token, ", "))
-		r.setUserAgent(req, nil)
+		r.setUserAgent(req)
 		res, err := r.client.Do(req)
 		if err != nil {
 			return nil, err
@@ -276,7 +282,7 @@ func (r *Registry) GetRepositoryData(indexEp, remote string) (*RepositoryData, e
 		req.SetBasicAuth(r.authConfig.Username, r.authConfig.Password)
 	}
 	req.Header.Set("X-Docker-Token", "true")
-	r.setUserAgent(req, nil)
+	r.setUserAgent(req)
 
 	res, err := r.client.Do(req)
 	if err != nil {
@@ -340,7 +346,7 @@ func (r *Registry) PushImageJSONRegistry(imgData *ImgData, jsonRaw []byte, regis
 	req.Header.Add("Content-type", "application/json")
 	req.Header.Set("Authorization", "Token "+strings.Join(token, ","))
 	req.Header.Set("X-Docker-Checksum", imgData.Checksum)
-	r.setUserAgent(req, nil)
+	r.setUserAgent(req)
 
 	utils.Debugf("Setting checksum for %s: %s", imgData.ID, imgData.Checksum)
 	res, err := doWithCookies(r.client, req)
@@ -375,7 +381,7 @@ func (r *Registry) PushImageLayerRegistry(imgID string, layer io.Reader, registr
 	req.ContentLength = -1
 	req.TransferEncoding = []string{"chunked"}
 	req.Header.Set("Authorization", "Token "+strings.Join(token, ","))
-	r.setUserAgent(req, nil)
+	r.setUserAgent(req)
 	res, err := doWithCookies(r.client, req)
 	if err != nil {
 		return fmt.Errorf("Failed to upload layer: %s", err)
@@ -413,7 +419,7 @@ func (r *Registry) PushRegistryTag(remote, revision, tag, registry string, token
 	}
 	req.Header.Add("Content-type", "application/json")
 	req.Header.Set("Authorization", "Token "+strings.Join(token, ","))
-	r.setUserAgent(req, nil)
+	r.setUserAgent(req)
 	req.ContentLength = int64(len(revision))
 	res, err := doWithCookies(r.client, req)
 	if err != nil {
@@ -446,7 +452,7 @@ func (r *Registry) PushImageJSONIndex(indexEp, remote string, imgList []*ImgData
 	req.SetBasicAuth(r.authConfig.Username, r.authConfig.Password)
 	req.ContentLength = int64(len(imgListJSON))
 	req.Header.Set("X-Docker-Token", "true")
-	r.setUserAgent(req, nil)
+	r.setUserAgent(req)
 	if validate {
 		req.Header["X-Docker-Endpoints"] = regs
 	}
@@ -467,7 +473,7 @@ func (r *Registry) PushImageJSONIndex(indexEp, remote string, imgList []*ImgData
 		req.SetBasicAuth(r.authConfig.Username, r.authConfig.Password)
 		req.ContentLength = int64(len(imgListJSON))
 		req.Header.Set("X-Docker-Token", "true")
-		r.setUserAgent(req, nil)
+		r.setUserAgent(req)
 		if validate {
 			req.Header["X-Docker-Endpoints"] = regs
 		}
diff --git a/server.go b/server.go
index b943ef2985..70bb0bb871 100644
--- a/server.go
+++ b/server.go
@@ -41,7 +41,7 @@ func (v *plainVersionChecker) Version() string {
 
 func (srv *Server) versionCheckers() []registry.VersionChecker {
 	v := srv.DockerVersion()
-	ret := make([]registry.VersionChecker, 0, 3)
+	ret := make([]registry.VersionChecker, 0, 4)
 	ret = append(ret, &plainVersionChecker{"docker", v.Version})
 
 	if len(v.GoVersion) > 0 {
@@ -50,6 +50,11 @@ func (srv *Server) versionCheckers() []registry.VersionChecker {
 	if len(v.GitCommit) > 0 {
 		ret = append(ret, &plainVersionChecker{"git-commit", v.GitCommit})
 	}
+	kernelVersion, err := utils.GetKernelVersion()
+	if err == nil {
+		ret = append(ret, &plainVersionChecker{"kernel", kernelVersion.String()})
+	}
+
 	return ret
 }