Index: /trunk/src/VBox/Main/GuestImpl.cpp
===================================================================
--- /trunk/src/VBox/Main/GuestImpl.cpp	(revision 31432)
+++ /trunk/src/VBox/Main/GuestImpl.cpp	(revision 31433)
@@ -1505,5 +1505,5 @@
 
     if (!aVersionName.isEmpty())
-        mData.mAdditionsVersion = aAdditionsVersion + " " + aVersionName;
+        mData.mAdditionsVersion = BstrFmt("%ls %ls", aAdditionsVersion.raw(), aVersionName.raw());
     else
         mData.mAdditionsVersion = aAdditionsVersion;