@@ -149,7 +149,7 @@ func (cli *DockerCli) hijack(method, path string, setRawTerminal bool, in io.Rea

 		req.Header.Set(k, v)

 	}

-	req.Header.Set("User-Agent", "Docker-Client/"+dockerversion.VERSION)

+	req.Header.Set("User-Agent", "Docker-Client/"+dockerversion.VERSION+" ("+runtime.GOOS+")")

 	req.Header.Set("Content-Type", "text/plain")

 	req.Header.Set("Connection", "Upgrade")

 	req.Header.Set("Upgrade", "tcp")

@@ -64,7 +64,7 @@ func (cli *DockerCli) clientRequest(method, path string, in io.Reader, headers m

 		req.Header.Set(k, v)

 	}

-	req.Header.Set("User-Agent", "Docker-Client/"+dockerversion.VERSION)

+	req.Header.Set("User-Agent", "Docker-Client/"+dockerversion.VERSION+" ("+runtime.GOOS+")")

 	req.URL.Host = cli.addr

 	req.URL.Scheme = cli.scheme

@@ -1459,6 +1459,13 @@ func makeHttpHandler(logging bool, localMethod string, localRoute string, handle

 		if strings.Contains(r.Header.Get("User-Agent"), "Docker-Client/") {

 			userAgent := strings.Split(r.Header.Get("User-Agent"), "/")

+

+			// v1.20 onwards includes the GOOS of the client after the version

+			// such as Docker/1.7.0 (linux)

+			if len(userAgent) == 2 && strings.Contains(userAgent[1], " ") {

+				userAgent[1] = strings.Split(userAgent[1], " ")[0]

+			}

+

 			if len(userAgent) == 2 && !dockerVersion.Equal(version.Version(userAgent[1])) {

 				logrus.Debugf("Warning: client and server don't have the same version (client: %s, server: %s)", userAgent[1], dockerVersion)

 			}

@@ -35,7 +35,7 @@ func (s *DockerSuite) TestVersionStatusCode(c *check.C) {

 	req, err := http.NewRequest("GET", "/v999.0/version", nil)

 	c.Assert(err, check.IsNil)

-	req.Header.Set("User-Agent", "Docker-Client/999.0")

+	req.Header.Set("User-Agent", "Docker-Client/999.0 (os)")

 	res, err := client.Do(req)

 	c.Assert(res.StatusCode, check.Equals, http.StatusBadRequest)

@@ -7,7 +7,9 @@ import (

 	"os"

 	"os/exec"

 	"path/filepath"

+	"runtime"

+	"github.com/docker/docker/autogen/dockerversion"

 	"github.com/docker/docker/pkg/homedir"

 	"github.com/go-check/check"

 )

@@ -50,6 +52,14 @@ func (s *DockerSuite) TestConfigHttpHeader(c *check.C) {

 	cmd := exec.Command(dockerBinary, "-H="+server.URL[7:], "ps")

 	out, _, _ := runCommandWithOutput(cmd)

+	if headers["User-Agent"] == nil {

+		c.Fatalf("Missing User-Agent: %q\nout:%v", headers, out)

+	}

+

+	if headers["User-Agent"][0] != "Docker-Client/"+dockerversion.VERSION+" ("+runtime.GOOS+")" {

+		c.Fatalf("Badly formatted User-Agent: %q\nout:%v", headers, out)

+	}

+

 	if headers["Myheader"] == nil || headers["Myheader"][0] != "MyValue" {

 		c.Fatalf("Missing/bad header: %q\nout:%v", headers, out)

 	}