diff --git a/h2quic/response_writer.go b/h2quic/response_writer.go
index 3499b4e1b..002a27458 100644
--- a/h2quic/response_writer.go
+++ b/h2quic/response_writer.go
@@ -6,15 +6,18 @@ import (
 	"net/http"
 	"strconv"
 
-	"github.com/lucas-clemente/quic-go"
 	"github.com/lucas-clemente/quic-go/protocol"
 	"github.com/lucas-clemente/quic-go/utils"
 	"golang.org/x/net/http2"
 	"golang.org/x/net/http2/hpack"
 )
 
+type streamCreator interface {
+	NewStream(protocol.StreamID) (utils.Stream, error)
+}
+
 type responseWriter struct {
-	session      *quic.Session
+	session      streamCreator
 	dataStreamID protocol.StreamID
 	headerStream utils.Stream
 	dataStream   utils.Stream
@@ -23,7 +26,7 @@ type responseWriter struct {
 	headerWritten bool
 }
 
-func newResponseWriter(headerStream utils.Stream, dataStreamID protocol.StreamID, session *quic.Session) *responseWriter {
+func newResponseWriter(headerStream utils.Stream, dataStreamID protocol.StreamID, session streamCreator) *responseWriter {
 	return &responseWriter{
 		header:       http.Header{},
 		headerStream: headerStream,
@@ -59,7 +62,6 @@ func (w *responseWriter) WriteHeader(status int) {
 	}
 }
 
-// TODO: Test
 func (w *responseWriter) Write(p []byte) (int, error) {
 	if !w.headerWritten {
 		w.WriteHeader(200)
diff --git a/h2quic/response_writer_test.go b/h2quic/response_writer_test.go
index 2c6e69cce..c3e395286 100644
--- a/h2quic/response_writer_test.go
+++ b/h2quic/response_writer_test.go
@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"net/http"
 
+	"github.com/lucas-clemente/quic-go/protocol"
+	"github.com/lucas-clemente/quic-go/utils"
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
 )
@@ -14,15 +16,28 @@ type mockStream struct {
 
 func (mockStream) Close() error { return nil }
 
+type mockSession struct {
+	stream *mockStream
+}
+
+func (s *mockSession) NewStream(id protocol.StreamID) (utils.Stream, error) {
+	Expect(id).To(Equal(protocol.StreamID(5)))
+	return s.stream, nil
+}
+
 var _ = Describe("Response Writer", func() {
 	var (
 		w            *responseWriter
 		headerStream *mockStream
+		dataStream   *mockStream
+		s            *mockSession
 	)
 
 	BeforeEach(func() {
 		headerStream = &mockStream{}
-		w = newResponseWriter(headerStream, 5, nil)
+		dataStream = &mockStream{}
+		s = &mockSession{stream: dataStream}
+		w = newResponseWriter(headerStream, 5, s)
 	})
 
 	It("writes status", func() {
@@ -41,4 +56,33 @@ var _ = Describe("Response Writer", func() {
 			0x2, 0x34, 0x32,
 		}))
 	})
+
+	It("writes data", func() {
+		n, err := w.Write([]byte("foobar"))
+		Expect(n).To(Equal(6))
+		Expect(err).ToNot(HaveOccurred())
+		// Should have written 200 on the header stream
+		Expect(headerStream.Bytes()).To(Equal([]byte{
+			0x0, 0x0, 0x1, 0x1, 0x4, 0x0, 0x0, 0x0, 0x5, 0x88,
+		}))
+		// And foobar on the data stream
+		Expect(dataStream.Bytes()).To(Equal([]byte{
+			0x66, 0x6f, 0x6f, 0x62, 0x61, 0x72,
+		}))
+	})
+
+	It("writes data after WriteHeader is called", func() {
+		w.WriteHeader(http.StatusTeapot)
+		n, err := w.Write([]byte("foobar"))
+		Expect(n).To(Equal(6))
+		Expect(err).ToNot(HaveOccurred())
+		// Should have written 418 on the header stream
+		Expect(headerStream.Bytes()).To(Equal([]byte{
+			0x0, 0x0, 0x5, 0x1, 0x4, 0x0, 0x0, 0x0, 0x5, 'H', 0x3, '4', '1', '8',
+		}))
+		// And foobar on the data stream
+		Expect(dataStream.Bytes()).To(Equal([]byte{
+			0x66, 0x6f, 0x6f, 0x62, 0x61, 0x72,
+		}))
+	})
 })