diff --git a/stream/stream.go b/stream/stream.go
index 7242df4..a4587a9 100644
--- a/stream/stream.go
+++ b/stream/stream.go
@@ -10,16 +10,32 @@ import (
 	"github.com/gotify/server/model"
 	"net/http"
 	"github.com/gotify/server/mode"
+	"net/url"
 )
 
 var upgrader = websocket.Upgrader{
 	ReadBufferSize:  1024,
 	WriteBufferSize: 1024,
 	CheckOrigin: func(r *http.Request) bool {
-		return mode.IsDev();
+		if mode.IsDev() {
+			return true
+		}
+		return checkSameOrigin(r)
 	},
 }
 
+func checkSameOrigin(r *http.Request) bool {
+	origin := r.Header["Origin"]
+	if len(origin) == 0 {
+		return true
+	}
+	u, err := url.Parse(origin[0])
+	if err != nil {
+		return false
+	}
+	return u.Host == r.Host
+}
+
 // The API provides a handler for a WebSocket stream API.
 type API struct {
 	clients     map[uint][]*client
diff --git a/stream/stream_test.go b/stream/stream_test.go
index d253611..5d23bc7 100644
--- a/stream/stream_test.go
+++ b/stream/stream_test.go
@@ -25,6 +25,8 @@ import (
 )
 
 func TestFailureOnNormalHttpRequest(t *testing.T) {
+	mode.Set(mode.TestDev)
+
 	defer leaktest.Check(t)()
 
 	server, api := bootTestServer(staticUserID())
@@ -38,6 +40,8 @@ func TestFailureOnNormalHttpRequest(t *testing.T) {
 }
 
 func TestWriteMessageFails(t *testing.T) {
+	mode.Set(mode.TestDev)
+
 	defer leaktest.Check(t)()
 
 	server, api := bootTestServer(func(context *gin.Context) {
@@ -65,6 +69,8 @@ func TestWriteMessageFails(t *testing.T) {
 }
 
 func TestWritePingFails(t *testing.T) {
+	mode.Set(mode.TestDev)
+
 	defer leaktest.CheckTimeout(t, 10*time.Second)()
 
 	server, api := bootTestServer(staticUserID())
@@ -92,6 +98,8 @@ func TestWritePingFails(t *testing.T) {
 }
 
 func TestPing(t *testing.T) {
+	mode.Set(mode.TestDev)
+
 	server, api := bootTestServer(staticUserID())
 	defer server.Close()
 	defer api.Close()
@@ -124,6 +132,8 @@ func TestPing(t *testing.T) {
 }
 
 func TestCloseClientOnNotReading(t *testing.T) {
+	mode.Set(mode.TestDev)
+
 	server, api := bootTestServer(staticUserID())
 	defer server.Close()
 	defer api.Close()
@@ -146,6 +156,7 @@ func TestCloseClientOnNotReading(t *testing.T) {
 }
 
 func TestMessageDirectlyAfterConnect(t *testing.T) {
+	mode.Set(mode.Prod)
 	defer leaktest.Check(t)()
 	server, api := bootTestServer(staticUserID())
 	defer server.Close()
@@ -162,6 +173,8 @@ func TestMessageDirectlyAfterConnect(t *testing.T) {
 }
 
 func TestMultipleClients(t *testing.T) {
+	mode.Set(mode.TestDev)
+
 	defer leaktest.Check(t)()
 	userIDs := []uint{1, 1, 1, 2, 2, 3}
 	i := 0
@@ -237,6 +250,37 @@ func TestMultipleClients(t *testing.T) {
 	expectNoMessage(userThree...)
 }
 
+func Test_sameOrigin_returnsTrue(t *testing.T) {
+	mode.Set(mode.Prod)
+	req := httptest.NewRequest("GET", "http://example.com/stream", nil)
+	req.Header.Set("Origin", "http://example.com")
+	actual := checkSameOrigin(req)
+	assert.True(t, actual)
+}
+
+func Test_emptyOrigin_returnsTrue(t *testing.T) {
+	mode.Set(mode.Prod)
+	req := httptest.NewRequest("GET", "http://example.com/stream", nil)
+	actual := checkSameOrigin(req)
+	assert.True(t, actual)
+}
+
+func Test_otherOrigin_returnsFalse(t *testing.T) {
+	mode.Set(mode.Prod)
+	req := httptest.NewRequest("GET", "http://example.com/stream", nil)
+	req.Header.Set("Origin", "http://otherexample.de")
+	actual := checkSameOrigin(req)
+	assert.False(t, actual)
+}
+
+func Test_invalidOrigin_returnsFalse(t *testing.T) {
+	mode.Set(mode.Prod)
+	req := httptest.NewRequest("GET", "http://example.com/stream", nil)
+	req.Header.Set("Origin", "http\\://otherexample.de")
+	actual := checkSameOrigin(req)
+	assert.False(t, actual)
+}
+
 func testClient(t *testing.T, url string) *testingClient {
 	ws, _, err := websocket.DefaultDialer.Dial(url, nil)
 	assert.Nil(t, err)
@@ -297,7 +341,6 @@ func (c *testingClient) expectNoMessage() {
 }
 
 func bootTestServer(handlerFunc gin.HandlerFunc) (*httptest.Server, *API) {
-	mode.Set(mode.TestDev)
 
 	r := gin.New()
 	r.Use(handlerFunc)