diff --git a/vncviewer/CConn.h b/vncviewer/CConn.h
index 709ca2f..1b92937 100644
--- a/vncviewer/CConn.h
+++ b/vncviewer/CConn.h
@@ -51,8 +51,8 @@
   void serverInit();
 
   void setDesktopSize(int w, int h);
-  void setExtendedDesktopSize(int reason, int result, int w, int h,
-                              const rfb::ScreenSet& layout);
+  void setExtendedDesktopSize(unsigned reason, unsigned result,
+                              int w, int h, const rfb::ScreenSet& layout);
 
   void setName(const char* name);