diff --git a/src/matrix-api.c b/src/matrix-api.c
index 46cddec..1e1d85a 100644
--- a/src/matrix-api.c
+++ b/src/matrix-api.c
@@ -1365,7 +1365,7 @@ matrix_api_redact_event(MatrixAPI *api,
  * @txn_id: the transaction ID for this event. Clients should generate
  *          a unique ID; it will be used by the server to ensure
  *          idempotency of requests
- * @content: the content of the event as a #JsonNode
+ * @content: (transfer full): the content of the event as a #JsonNode
  * @error: return location for a #GError, or %NULL
  *
  * Send a message event to the room.
@@ -1377,7 +1377,7 @@ matrix_api_send_message_event(MatrixAPI *api,
                               const gchar *room_id,
                               const gchar *event_type,
                               const gchar *txn_id,
-                              const JsonNode *content,
+                              JsonNode *content,
                               GError **error)
 {
     g_return_if_fail(MATRIX_IS_API(api));
diff --git a/src/matrix-api.h b/src/matrix-api.h
index 7cdbbcf..51f5012 100644
--- a/src/matrix-api.h
+++ b/src/matrix-api.h
@@ -298,7 +298,7 @@ struct _MatrixAPIInterface {
                                const gchar *room_id,
                                const gchar *event_type,
                                const gchar *txn_id,
-                               const JsonNode *content,
+                               JsonNode *content,
                                GError **error);
     void (*get_room_state)(MatrixAPI *api,
                            MatrixAPICallback callback,
@@ -715,7 +715,7 @@ void matrix_api_send_message_event(MatrixAPI *api,
                                    const gchar *room_id,
                                    const gchar *event_type,
                                    const gchar *txn_id,
-                                   const JsonNode *content,
+                                   JsonNode *content,
                                    GError **error);
 void matrix_api_get_room_state(MatrixAPI *api,
                                MatrixAPICallback callback,