diff --git a/integration/watermill/mpv2/metadata.go b/integration/watermill/mpv2/metadata.go
new file mode 100644
index 0000000..c174b14
--- /dev/null
+++ b/integration/watermill/mpv2/metadata.go
@@ -0,0 +1,5 @@
+package mpv2
+
+const (
+	MetadataRequestQuery = "RequestQuery"
+)
diff --git a/integration/watermill/mpv2/publisher.go b/integration/watermill/mpv2/publisher.go
index 738fdf0..425d74f 100644
--- a/integration/watermill/mpv2/publisher.go
+++ b/integration/watermill/mpv2/publisher.go
@@ -119,17 +119,20 @@ func (p *Publisher) handle(l *zap.Logger, msg *message.Message) error {
 		return errors.Wrap(err, "failed to create request")
 	}
 
-	for s, s2 := range msg.Metadata {
-		if s == "Cookie" {
-			for _, s3 := range strings.Split(s2, "; ") {
+	for key, value := range msg.Metadata {
+		switch key {
+		case "Cookie":
+			for _, s3 := range strings.Split(value, "; ") {
 				val := strings.Split(s3, "=")
 				req.AddCookie(&http.Cookie{
 					Name:  val[0],
 					Value: strings.Join(val[1:], "="),
 				})
 			}
-		} else {
-			req.Header.Set(s, s2)
+		case MetadataRequestQuery:
+			req.URL.RawQuery = value
+		default:
+			req.Header.Set(key, value)
 		}
 	}
 
diff --git a/integration/watermill/mpv2/subscriber.go b/integration/watermill/mpv2/subscriber.go
index 543e66e..e9b0a8a 100644
--- a/integration/watermill/mpv2/subscriber.go
+++ b/integration/watermill/mpv2/subscriber.go
@@ -119,6 +119,10 @@ func (s *Subscriber) handle(l *zap.Logger, r *http.Request, payload *mpv2.Payloa
 	l = l.With(zap.String("message_id", msg.UUID))
 	msg.SetContext(context.WithoutCancel(r.Context()))
 
+	// store query
+	msg.Metadata.Set(MetadataRequestQuery, r.URL.RawQuery)
+
+	// store header
 	for name, headers := range r.Header {
 		msg.Metadata.Set(name, strings.Join(headers, ","))
 	}
diff --git a/pkg/client/mpv2.go b/pkg/client/mpv2.go
index 772ec9a..8bc797a 100644
--- a/pkg/client/mpv2.go
+++ b/pkg/client/mpv2.go
@@ -16,11 +16,15 @@ import (
 
 type (
 	MPv2 struct {
-		l               *zap.Logger
-		path            string
-		host            string
-		cookies         []string
-		apiSecret       string
+		l       *zap.Logger
+		path    string
+		host    string
+		cookies []string
+		// To create a new secret, navigate in the Google Analytics UI to:
+		// Admin > Data Streams > choose your stream > Measurement Protocol > Create
+		apiSecret string
+		// Measurement ID. The identifier for a Data Stream. Found in the Google Analytics UI under:
+		// Admin > Data Streams > choose your stream > Measurement ID
 		measurementID   string
 		protocolVersion string
 		httpClient      *http.Client
@@ -139,6 +143,7 @@ func (c *MPv2) SendRaw(r *http.Request, payload *mpv2.Payload[any]) error {
 		return errors.Wrap(err, "failed to create request")
 	}
 
+	// query
 	qry := req.URL.Query()
 	if len(c.apiSecret) > 0 {
 		qry.Add("api_secret", c.apiSecret)