diff --git a/common/rfb/SMsgWriterV3.cxx b/common/rfb/SMsgWriterV3.cxx
index 6f0aed0..08f5a2e 100644
--- a/common/rfb/SMsgWriterV3.cxx
+++ b/common/rfb/SMsgWriterV3.cxx
@@ -221,7 +221,7 @@
   endMsg();
 }
 
-void SMsgWriterV3::startRect(const Rect& r, unsigned int encoding)
+void SMsgWriterV3::startRect(const Rect& r, int encoding)
 {
   if (++nRectsInUpdate > nRectsInHeader && nRectsInHeader)
     throw Exception("SMsgWriterV3::startRect: nRects out of sync");