diff --git a/tunnels/client/protobuf/protobuf_client.c b/tunnels/client/protobuf/protobuf_client.c
index 4a47ad3..57b5aa3 100644
--- a/tunnels/client/protobuf/protobuf_client.c
+++ b/tunnels/client/protobuf/protobuf_client.c
@@ -124,7 +124,7 @@ static void downStream(tunnel_t *self, context_t *c)
                 shiftr(full_data, sizeof(uint32_t));
                 cstate->bytes_sent_nack -= consumed;
 
-                if (cstate->bytes_sent_nack < kMaxSendBeforeAck / 2)
+                if (cstate->bytes_sent_nack <=kMaxSendBeforeAck / 3)
                 {
                     resumeLineDownSide(c->line);
                 }
diff --git a/tunnels/server/protobuf/protobuf_server.c b/tunnels/server/protobuf/protobuf_server.c
index 0869552..a598d81 100644
--- a/tunnels/server/protobuf/protobuf_server.c
+++ b/tunnels/server/protobuf/protobuf_server.c
@@ -94,7 +94,7 @@ static void upStream(tunnel_t *self, context_t *c)
 
                 cstate->bytes_sent_nack -= consumed;
 
-                if (cstate->bytes_sent_nack < kMaxSendBeforeAck / 2)
+                if (cstate->bytes_sent_nack <= kMaxSendBeforeAck / 3)
                 {
                     resumeLineUpSide(c->line);
                 }