diff --git a/transport/http/jsonrpc/server.go b/transport/http/jsonrpc/server.go
index 0310f3e..75666e4 100644
--- a/transport/http/jsonrpc/server.go
+++ b/transport/http/jsonrpc/server.go
@@ -10,6 +10,10 @@
 	"github.com/go-kit/kit/log"
 	httptransport "github.com/go-kit/kit/transport/http"
 )
+
+type requestIDKeyType struct{}
+
+var requestIDKey requestIDKeyType
 
 // Server wraps an endpoint and implements http.Handler.
 type Server struct {
@@ -105,6 +109,8 @@
 		return
 	}
 
+	ctx = context.WithValue(ctx, requestIDKey, req.ID)
+
 	// Get the endpoint and codecs from the map using the method
 	// defined in the JSON  object
 	ecm, ok := s.ecm[req.Method]
@@ -160,7 +166,7 @@
 // If the error implements ErrorCoder, the provided code will be set on the
 // response error.
 // If the error implements Headerer, the given headers will be set.
-func DefaultErrorEncoder(_ context.Context, err error, w http.ResponseWriter) {
+func DefaultErrorEncoder(ctx context.Context, err error, w http.ResponseWriter) {
 	w.Header().Set("Content-Type", ContentType)
 	if headerer, ok := err.(httptransport.Headerer); ok {
 		for k := range headerer.Headers() {
@@ -177,7 +183,13 @@
 	}
 
 	w.WriteHeader(http.StatusOK)
+
+	var requestID *RequestID
+	if v := ctx.Value(requestIDKey); v != nil {
+		requestID = v.(*RequestID)
+	}
 	_ = json.NewEncoder(w).Encode(Response{
+		ID:      requestID,
 		JSONRPC: Version,
 		Error:   &e,
 	})
diff --git a/transport/http/jsonrpc/server_test.go b/transport/http/jsonrpc/server_test.go
index d7960fe..c279d3c 100644
--- a/transport/http/jsonrpc/server_test.go
+++ b/transport/http/jsonrpc/server_test.go
@@ -24,17 +24,51 @@
 	return strings.NewReader(in)
 }
 
+func unmarshalResponse(body []byte) (resp jsonrpc.Response, err error) {
+	err = json.Unmarshal(body, &resp)
+	return
+}
+
 func expectErrorCode(t *testing.T, want int, body []byte) {
-	var r jsonrpc.Response
-	err := json.Unmarshal(body, &r)
-	if err != nil {
-		t.Fatalf("Cant' decode response. err=%s, body=%s", err, body)
+	t.Helper()
+
+	r, err := unmarshalResponse(body)
+	if err != nil {
+		t.Fatalf("Can't decode response: %v (%s)", err, body)
 	}
 	if r.Error == nil {
 		t.Fatalf("Expected error on response. Got none: %s", body)
 	}
 	if have := r.Error.Code; want != have {
 		t.Fatalf("Unexpected error code. Want %d, have %d: %s", want, have, body)
+	}
+}
+
+func expectValidRequestID(t *testing.T, want int, body []byte) {
+	t.Helper()
+
+	r, err := unmarshalResponse(body)
+	if err != nil {
+		t.Fatalf("Can't decode response: %v (%s)", err, body)
+	}
+	have, err := r.ID.Int()
+	if err != nil {
+		t.Fatalf("Can't get requestID in response. err=%s, body=%s", err, body)
+	}
+	if want != have {
+		t.Fatalf("Request ID: want %d, have %d (%s)", want, have, body)
+	}
+}
+
+func expectNilRequestID(t *testing.T, body []byte) {
+	t.Helper()
+
+	r, err := unmarshalResponse(body)
+	if err != nil {
+		t.Fatalf("Can't decode response: %v (%s)", err, body)
+	}
+	if r.ID != nil {
+		t.Fatalf("Request ID: want nil, have %v", r.ID)
 	}
 }
 
@@ -92,6 +126,7 @@
 	}
 	buf, _ := ioutil.ReadAll(resp.Body)
 	expectErrorCode(t, jsonrpc.InternalError, buf)
+	expectValidRequestID(t, 1, buf)
 }
 
 func TestServerBadEncode(t *testing.T) {
@@ -111,6 +146,7 @@
 	}
 	buf, _ := ioutil.ReadAll(resp.Body)
 	expectErrorCode(t, jsonrpc.InternalError, buf)
+	expectValidRequestID(t, 1, buf)
 }
 
 func TestServerErrorEncoder(t *testing.T) {
@@ -162,6 +198,7 @@
 	}
 	buf, _ := ioutil.ReadAll(resp.Body)
 	expectErrorCode(t, jsonrpc.ParseError, buf)
+	expectNilRequestID(t, buf)
 }
 
 func TestServerUnregisteredMethod(t *testing.T) {
@@ -186,10 +223,9 @@
 	if want, have := http.StatusOK, resp.StatusCode; want != have {
 		t.Errorf("want %d, have %d (%s)", want, have, buf)
 	}
-	var r jsonrpc.Response
-	err := json.Unmarshal(buf, &r)
-	if err != nil {
-		t.Fatalf("Cant' decode response. err=%s, body=%s", err, buf)
+	r, err := unmarshalResponse(buf)
+	if err != nil {
+		t.Fatalf("Can't decode response. err=%s, body=%s", err, buf)
 	}
 	if r.JSONRPC != jsonrpc.Version {
 		t.Fatalf("JSONRPC Version: want=%s, got=%s", jsonrpc.Version, r.JSONRPC)