diff --git a/luprex/cpp/core/lpxclient.cpp b/luprex/cpp/core/lpxclient.cpp
index 076023ea..02d1d345 100644
--- a/luprex/cpp/core/lpxclient.cpp
+++ b/luprex/cpp/core/lpxclient.cpp
@@ -95,7 +95,6 @@ public:
         StreamBuffer *sb = channel_->out();
         sb->write_uint8(util::MSG_INVOKE);
         inv.serialize(sb);
-        util::dprint("Sent ", inv.debug_string());
     }
 
     void send_lua_source(const util::LuaSourceVec &sv) {
@@ -228,7 +227,6 @@ public:
             receive_ack_from_server(&body);
         } else if (message_type == util::MSG_DIFF) {
             receive_diff_from_server(&body);
-            util::dprintf("Executed diff from server");
         } else {
             abandon_server();
             return false;
diff --git a/luprex/cpp/core/lpxserver.cpp b/luprex/cpp/core/lpxserver.cpp
index c9f018de..9aa9c01d 100644
--- a/luprex/cpp/core/lpxserver.cpp
+++ b/luprex/cpp/core/lpxserver.cpp
@@ -126,7 +126,7 @@ public:
         sb->write_uint8(util::MSG_DIFF);
         sb->write_uint32(0);
         int64_t tw_1 = sb->total_writes();
-        stdostream() << "Sending diffs to client " << client->actor_id_ << std::endl;
+        //stdostream() << "Sending diffs to client " << client->actor_id_ << std::endl;
         client->sync_->diff_everything(client->actor_id_, master_.get(), sb);
         int64_t tw_2 = sb->total_writes();
         sb->overwrite_int32(tw_1, tw_2 - tw_1);
@@ -150,12 +150,11 @@ public:
             delete_client(client);
             return false;
         }
-        util::dprint("Received ", inv.debug_string());
         if (inv.actor() != client->actor_id_) {
             stdostream() << "Ignoring invoke with wrong actor ID " << inv.actor() << std::endl;
             return true;
         }
-        stdostream() << "Invoking: " << inv.debug_string() << std::endl;
+        //stdostream() << "Invoking: " << inv.debug_string() << std::endl;
         master_->invoke(inv);
         client->channel_->out()->write_uint8(util::MSG_ACK);
         client->channel_->out()->write_uint32(0);
diff --git a/luprex/cpp/drv/driver-common.cpp b/luprex/cpp/drv/driver-common.cpp
index d35515c5..be82e7d0 100644
--- a/luprex/cpp/drv/driver-common.cpp
+++ b/luprex/cpp/drv/driver-common.cpp
@@ -444,6 +444,9 @@ class Driver {
         bool any_released = false;
         for (ChanInfo &chan : chans_) {
             engw.get_outgoing(&engw, chan.chid, &chan.nbytes, &chan.bytes);
+            if (chan.nbytes > 0) {
+                chan.need_advance = true;
+            }
             if (chan.nbytes == 0) {
                 if (engw.get_channel_released(&engw, chan.chid)) {
                     close_channel(chan, "");