diff --git a/build/VStudio/installer/Product.wxs b/build/VStudio/installer/Product.wxs
index dcb165e4..2b74c95d 100644
--- a/build/VStudio/installer/Product.wxs
+++ b/build/VStudio/installer/Product.wxs
@@ -66,7 +66,7 @@
             NOT INSTALLDIR
         </SetProperty>
         <SetProperty Id="SXSDIR" Value="[INSTALLDIR]SxS\sxs.[InstanceID]\" After="SetINSTALLDIR">
-            NOT SXSDIR
+            ((NOT SXSDIR) OR WIX_UPGRADE_DETECTED) AND InstanceID
         </SetProperty>
 
         <!-- Setup directory structure. -->