diff --git a/pkg/services/matrix/matrix_api.go b/pkg/services/matrix/matrix_api.go
index abf29213..625b0cf8 100644
--- a/pkg/services/matrix/matrix_api.go
+++ b/pkg/services/matrix/matrix_api.go
@@ -7,7 +7,7 @@ type identifierType string
 const (
 	apiLogin       = "/_matrix/client/r0/login"
 	apiRoomJoin    = "/_matrix/client/r0/join/%s"
-	apiSendMessage = "/_matrix/client/r0/rooms/%s/send/m.room.message"
+	apiSendMessage = "/_matrix/client/r0/rooms/%s/send/m.room.message/%v"
 	apiJoinedRooms = "/_matrix/client/r0/joined_rooms"
 
 	contentType = "application/json"
diff --git a/pkg/services/matrix/matrix_client.go b/pkg/services/matrix/matrix_client.go
index 6d9de36c..68025968 100644
--- a/pkg/services/matrix/matrix_client.go
+++ b/pkg/services/matrix/matrix_client.go
@@ -8,6 +8,7 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"sync/atomic"
 
 	"github.com/containrrr/shoutrrr/pkg/types"
 	"github.com/containrrr/shoutrrr/pkg/util"
@@ -17,6 +18,7 @@ type client struct {
 	apiURL      url.URL
 	accessToken string
 	logger      types.StdLogger
+	counter     uint64
 }
 
 func newClient(host string, disableTLS bool, logger types.StdLogger) (c *client) {
@@ -41,6 +43,10 @@ func newClient(host string, disableTLS bool, logger types.StdLogger) (c *client)
 	return c
 }
 
+func (c *client) txId() uint64 {
+	return atomic.AddUint64(&c.counter, 1)
+}
+
 func (c *client) useToken(token string) {
 	c.accessToken = token
 	c.updateAccessToken()
@@ -148,7 +154,7 @@ func (c *client) joinRoom(room string) (roomID string, err error) {
 
 func (c *client) sendMessageToRoom(message string, roomID string) error {
 	resEvent := apiResEvent{}
-	return c.apiPost(fmt.Sprintf(apiSendMessage, roomID), apiReqSend{
+	return c.apiPost(fmt.Sprintf(apiSendMessage, roomID, c.txId()), apiReqSend{
 		MsgType: msgTypeText,
 		Body:    message,
 	}, &resEvent)
diff --git a/pkg/services/matrix/matrix_test.go b/pkg/services/matrix/matrix_test.go
index abf73009..cf3f2763 100644
--- a/pkg/services/matrix/matrix_test.go
+++ b/pkg/services/matrix/matrix_test.go
@@ -167,13 +167,13 @@ func setupMockResponders() {
 		mockServer+apiJoinedRooms,
 		httpmock.NewStringResponder(200, `{ "joined_rooms": [ "!room:mockserver" ] }`))
 
-	httpmock.RegisterResponder("POST", mockServer+fmt.Sprintf(apiSendMessage, "%21room:mockserver"),
+	httpmock.RegisterResponder("POST", `=~`+mockServer+fmt.Sprintf(apiSendMessage, "%21room:mockserver", `[0-9]+`),
 		httpmock.NewJsonResponderOrPanic(200, apiResEvent{EventID: "7"}))
 
-	httpmock.RegisterResponder("POST", mockServer+fmt.Sprintf(apiSendMessage, "1"),
+	httpmock.RegisterResponder("POST", `=~`+mockServer+fmt.Sprintf(apiSendMessage, "1", `[0-9]+`),
 		httpmock.NewJsonResponderOrPanic(200, apiResEvent{EventID: "8"}))
 
-	httpmock.RegisterResponder("POST", mockServer+fmt.Sprintf(apiSendMessage, "2"),
+	httpmock.RegisterResponder("POST", `=~`+mockServer+fmt.Sprintf(apiSendMessage, "2", `[0-9]+`),
 		httpmock.NewJsonResponderOrPanic(200, apiResEvent{EventID: "9"}))
 
 	httpmock.RegisterResponder("POST", mockServer+fmt.Sprintf(apiRoomJoin, "%23room1"),