diff --git a/src/networking.c b/src/networking.c
index ff3d951ffd1430c4dcd6c7a70dcf68f5471257a6..4233dd306be39d57b7fa25ea3fc2dde71d6ef08d 100644
--- a/src/networking.c
+++ b/src/networking.c
@@ -813,7 +813,13 @@ void sendReplyToClient(aeEventLoop *el, int fd, void *privdata, int mask) {
             return;
         }
     }
-    if (totwritten > 0) c->lastinteraction = server.unixtime;
+    if (totwritten > 0) {
+        /* For clients representing masters we don't count sending data
+         * as an interaction, since we always send REPLCONF ACK commands
+         * that take some time to just fill the socket output buffer.
+         * We just rely on data / pings received for timeout detection. */
+        if (!(c->flags & REDIS_MASTER)) c->lastinteraction = server.unixtime;
+    }
     if (c->bufpos == 0 && listLength(c->reply) == 0) {
         c->sentlen = 0;
         aeDeleteFileEvent(server.el,c->fd,AE_WRITABLE);