diff --git a/common/rfb/encodings.h b/common/rfb/encodings.h
index 1021be9..2f3b430 100644
--- a/common/rfb/encodings.h
+++ b/common/rfb/encodings.h
@@ -33,6 +33,7 @@
   const unsigned int pseudoEncodingXCursor = 0xffffff10;
   const unsigned int pseudoEncodingCursor = 0xffffff11;
   const unsigned int pseudoEncodingDesktopSize = 0xffffff21;
+  const unsigned int pseudoEncodingExtendedDesktopSize = 0xfffffecb; // FIXME: Unofficial
   const unsigned int pseudoEncodingDesktopName = 0xfffffecdl;
 
   // TightVNC-specific