diff --git a/examples/simple_room_server/main.cpp b/examples/simple_room_server/main.cpp
index a01dc99..cd92790 100644
--- a/examples/simple_room_server/main.cpp
+++ b/examples/simple_room_server/main.cpp
@@ -213,7 +213,7 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
     memcpy(&reply_data[len], post.text, text_len); len += text_len;
 
     // calc expected ACK reply
-    mesh::Utils::sha256((uint8_t *)&client->pending_ack, 4, reply_data, len, self_id.pub_key, PUB_KEY_SIZE);
+    mesh::Utils::sha256((uint8_t *)&client->pending_ack, 4, reply_data, len, client->id.pub_key, PUB_KEY_SIZE);
     client->push_post_timestamp = post.post_timestamp;
 
     auto reply = createDatagram(PAYLOAD_TYPE_TXT_MSG, client->id, client->secret, reply_data, len);
diff --git a/src/helpers/BaseChatMesh.cpp b/src/helpers/BaseChatMesh.cpp
index b61a0d3..e8e48e5 100644
--- a/src/helpers/BaseChatMesh.cpp
+++ b/src/helpers/BaseChatMesh.cpp
@@ -140,8 +140,8 @@ void BaseChatMesh::onPeerDataRecv(mesh::Packet* packet, uint8_t type, int sender
       }
       onSignedMessageRecv(from, packet->isRouteFlood() ? packet->path_len : 0xFF, timestamp, &data[5], (const char *) &data[9]);  // let UI know
 
-      uint32_t ack_hash;    // calc truncated hash of the message timestamp + text + sender pub_key, to prove to sender that we got it
-      mesh::Utils::sha256((uint8_t *) &ack_hash, 4, data, 9 + strlen((char *)&data[9]), from.id.pub_key, PUB_KEY_SIZE);
+      uint32_t ack_hash;    // calc truncated hash of the message timestamp + text + OUR pub_key, to prove to sender that we got it
+      mesh::Utils::sha256((uint8_t *) &ack_hash, 4, data, 9 + strlen((char *)&data[9]), self_id.pub_key, PUB_KEY_SIZE);
 
       if (packet->isRouteFlood()) {
         // let this sender know path TO here, so they can use sendDirect(), and ALSO encode the ACK