diff --git a/common/rfb/SMsgWriter.cxx b/common/rfb/SMsgWriter.cxx
index e421508..5040b65 100644
--- a/common/rfb/SMsgWriter.cxx
+++ b/common/rfb/SMsgWriter.cxx
@@ -285,6 +285,7 @@
 
 void SMsgWriter::endRect()
 {
+  os->flush();
 }
 
 void SMsgWriter::startMsg(int type)