diff --git a/src/core/engines/noweb/session.noweb.core.ts b/src/core/engines/noweb/session.noweb.core.ts
index 8a78a23a..375df208 100644
--- a/src/core/engines/noweb/session.noweb.core.ts
+++ b/src/core/engines/noweb/session.noweb.core.ts
@@ -642,10 +642,13 @@ export class WhatsappSessionNoWebCore extends WhatsappSession {
 
   async sendSeen(request: SendSeenRequest) {
     const key = parseMessageId(request.messageId);
+    const participant = request.participant
+      ? toJID(this.ensureSuffix(request.participant))
+      : undefined;
     const data = {
       remoteJid: key.remoteJid,
       id: key.id,
-      participant: request.participant,
+      participant: participant,
     };
     return this.sock.readMessages([data]);
   }
diff --git a/src/structures/chatting.dto.ts b/src/structures/chatting.dto.ts
index dcfa6ddf..a12ce646 100644
--- a/src/structures/chatting.dto.ts
+++ b/src/structures/chatting.dto.ts
@@ -72,6 +72,7 @@ export class SendSeenRequest extends ChatRequest {
   @ApiProperty({
     example: '11111111111@c.us',
     required: false,
+    default: null,
     description:
       'NOWEB engine only - the ID of the user that sent the  message (undefined for individual chats)',
   })