Index: /trunk/include/iprt/cdefs.h
===================================================================
--- /trunk/include/iprt/cdefs.h	(revision 58176)
+++ /trunk/include/iprt/cdefs.h	(revision 58177)
@@ -1417,6 +1417,19 @@
 /** @def RT_XSTR
  * Returns the expanded argument as a string.
- * @param   str     Argument to expand and stringy. */
+ * @param   str     Argument to expand and stringify. */
 #define RT_XSTR(str)            RT_STR(str)
+
+/** @def RT_LSTR_2
+ * Helper for RT_WSTR that gets the expanded @a str.
+ * @param   str     String litteral to prefix with 'L'.  */
+#define RT_LSTR_2(str)          L##str
+/** @def RT_LSTR
+ * Returns the expanded argument with a L string prefix.
+ *
+ * Intended for converting ASCII string \#defines into wide char string
+ * litterals on Windows.
+ *
+ * @param   str     String litteral to . */
+#define RT_LSTR(str)            RT_LSTR_2(str)
 
 /** @def RT_CONCAT
Index: /trunk/src/VBox/Additions/common/VBoxGuestLib/VBoxGuestR3LibAdditions.cpp
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxGuestLib/VBoxGuestR3LibAdditions.cpp	(revision 58176)
+++ /trunk/src/VBox/Additions/common/VBoxGuestLib/VBoxGuestR3LibAdditions.cpp	(revision 58177)
@@ -40,7 +40,4 @@
 #ifdef RT_OS_WINDOWS
 
-# define WIDE_STR_2(a) L##a
-# define WIDE_STR(a) WIDE_STR_2(a)
-
 /**
  * Opens the "VirtualBox Guest Additions" registry key.
@@ -58,7 +55,7 @@
     static PCRTUTF16 s_apwszKeys[] =
     {
-        L"SOFTWARE\\" WIDE_STR(VBOX_VENDOR_SHORT) L"\\VirtualBox Guest Additions",
+        L"SOFTWARE\\" RT_LSTR(VBOX_VENDOR_SHORT) L"\\VirtualBox Guest Additions",
 #ifdef RT_ARCH_AMD64
-        L"SOFTWARE\\Wow6432Node\\" WIDE_STR(VBOX_VENDOR_SHORT) L"\\VirtualBox Guest Additions",
+        L"SOFTWARE\\Wow6432Node\\" RT_LSTR(VBOX_VENDOR_SHORT) L"\\VirtualBox Guest Additions",
 #endif
         L"SOFTWARE\\Sun\\VirtualBox Guest Additions",