diff --git a/common/rfb/VNCSConnectionST.cxx b/common/rfb/VNCSConnectionST.cxx
index 77a6058..3f92a42 100644
--- a/common/rfb/VNCSConnectionST.cxx
+++ b/common/rfb/VNCSConnectionST.cxx
@@ -1067,8 +1067,20 @@
 
   if (!ui.is_empty())
     encodeManager.writeUpdate(ui, server->getPixelBuffer(), cursor);
-  else
-    encodeManager.writeLosslessRefresh(req, server->getPixelBuffer(), cursor);
+  else {
+    size_t maxUpdateSize;
+
+    // FIXME: If continuous updates aren't used then the client might
+    //        be slower than frameRate in its requests and we could
+    //        afford a larger update size
+
+    // FIXME: Bandwidth estimation without congestion control
+    maxUpdateSize = congestion.getBandwidth() *
+                    server->msToNextUpdate() / 1000;
+
+    encodeManager.writeLosslessRefresh(req, server->getPixelBuffer(),
+                                       cursor, maxUpdateSize);
+  }
 
   writeRTTPing();