diff --git a/src/networking.c b/src/networking.c
index 7976caf29..9ff2afd8d 100644
--- a/src/networking.c
+++ b/src/networking.c
@@ -2475,7 +2475,8 @@ void flushSlavesOutputBuffers(void) {
          * case the writable event is never installed, since the purpose
          * of put_online_on_ack is to postpone the moment it is installed.
          * This is what we want since slaves in this state should not receive
-         * writes before the first ACK. */
+         * writes before the first ACK (to know the reason, grep for this
+         * flag in this file). */
         events = aeGetFileEvents(server.el,slave->fd);
         if (events & AE_WRITABLE &&
             slave->replstate == SLAVE_STATE_ONLINE &&