diff --git a/win/rfb_win32/Registry.cxx b/win/rfb_win32/Registry.cxx
index 4f073f4..b278576 100644
--- a/win/rfb_win32/Registry.cxx
+++ b/win/rfb_win32/Registry.cxx
@@ -246,7 +246,7 @@
   case REG_DWORD:
     {
       TCharArray tmp(16);
-      _stprintf(tmp.buf, _T("%u"), *((DWORD*)data.buf));
+      _stprintf(tmp.buf, _T("%lu"), *((DWORD*)data.buf));
       return tmp.takeBuf();
     }
   case REG_EXPAND_SZ: