Index: /trunk/src/VBox/Main/src-client/GuestSessionImplTasks.cpp
===================================================================
--- /trunk/src/VBox/Main/src-client/GuestSessionImplTasks.cpp	(revision 71818)
+++ /trunk/src/VBox/Main/src-client/GuestSessionImplTasks.cpp	(revision 71819)
@@ -642,9 +642,9 @@
         }
 
-        rc = dstFile->i_writeData(uTimeoutMs, byBuf, cbRead, NULL /* No partial writes */);
+        rc = dstFile->i_writeData(uTimeoutMs, byBuf, (uint32_t)cbRead, NULL /* No partial writes */);
         if (RT_FAILURE(rc))
         {
             setProgressErrorMsg(VBOX_E_IPRT_ERROR,
-                                Utf8StrFmt(GuestSession::tr("Writing to %RU32 bytes to file failed: %Rrc"), cbRead, rc));
+                                Utf8StrFmt(GuestSession::tr("Writing to %zu bytes to file failed: %Rrc"), cbRead, rc));
             break;
         }