diff --git a/common/rfb/CMsgWriter.h b/common/rfb/CMsgWriter.h
index 5794f91..37755e7 100644
--- a/common/rfb/CMsgWriter.h
+++ b/common/rfb/CMsgWriter.h
@@ -23,6 +23,7 @@
 #define __RFB_CMSGWRITER_H__
 
 #include <rfb/InputHandler.h>
+#include <rfb/ScreenSet.h>
 
 namespace rdr { class OutStream; }
 
@@ -41,6 +42,9 @@
     virtual void startMsg(int type)=0;
     virtual void endMsg()=0;
 
+    virtual void writeSetDesktopSize(int width, int height,
+                                     const ScreenSet& layout)=0;
+
     // CMsgWriter implemented methods
     virtual void writeSetPixelFormat(const PixelFormat& pf);
     virtual void writeSetEncodings(int nEncodings, rdr::U32* encodings);