session_client DOC clarification
diff --git a/src/session_client.h b/src/session_client.h
index 96b9045..5aad755 100644
--- a/src/session_client.h
+++ b/src/session_client.h
@@ -548,6 +548,8 @@
 /**
  * @brief Receive NETCONF RPC reply.
  *
+ * @note This function can be called in a single thread only.
+ *
  * @param[in] session NETCONF session from which the function gets data. It must be the
  * client side session object.
  * @param[in] rpc Original RPC this should be the reply to.