diff --git a/trunk/c5/regtest.cpp b/trunk/c5/regtest.cpp
index ba46633f..b89eaad3 100644
--- a/trunk/c5/regtest.cpp
+++ b/trunk/c5/regtest.cpp
@@ -1,6 +1,6 @@
 #include "factory.h"
 
-#define CRYPTOPP_ENABLE_NAMESPACE_WEAK
+#define CRYPTOPP_ENABLE_NAMESPACE_WEAK 1
 #include "modes.h"
 #include "dh.h"
 #include "esign.h"