diff --git a/Source/CPack/WiX/cmCPackWIXGenerator.cxx b/Source/CPack/WiX/cmCPackWIXGenerator.cxx
index 6e8c5ea0fb6917a7623ea8f37b43dd8e85b24a97..68ca60eeab68492d9eeb6cd84d517d0ec481f16b 100644
--- a/Source/CPack/WiX/cmCPackWIXGenerator.cxx
+++ b/Source/CPack/WiX/cmCPackWIXGenerator.cxx
@@ -539,8 +539,8 @@ std::string cmCPackWIXGenerator::GenerateGUID()
   UUID guid;
   UuidCreate(&guid);
 
-  RPC_CSTR tmp = 0;
-  UuidToStringA(&guid, &tmp);
+  unsigned char *tmp = 0;
+  UuidToString(&guid, &tmp);
 
   std::string result(reinterpret_cast<char*>(tmp));
   RpcStringFree(&tmp);