diff --git a/xpinstall/wizard/windows/setup/extra.c b/xpinstall/wizard/windows/setup/extra.c
index f1330e390a9f..6808c4855abb 100644
--- a/xpinstall/wizard/windows/setup/extra.c
+++ b/xpinstall/wizard/windows/setup/extra.c
@@ -1829,7 +1829,7 @@ HRESULT VerifyDiskSpace()
     ullDSTotalAvailable = ullDSAPath;
 
     if(ullDSTotalAvailable < ullDSTotalRequired)
-      return(ErrorMsgDiskSpace(ullDSAPath, ullDSRPath, sgProduct.szPath, FALSE));
+      return(ErrorMsgDiskSpace(ullDSTotalAvailable, ullDSTotalRequired, sgProduct.szPath, FALSE));
   }
   else
   {