Index: include/apr.hw
===================================================================
--- include/apr.hw	(revision 606840)
+++ include/apr.hw	(working copy)
@@ -77,8 +77,10 @@
 #ifndef _WIN32_WINNT
 
 /* Restrict the server to a subset of Windows NT 4.0 header files by default
+ *
+ * In order to use the MCAST API - 0x0501 is required!
  */
-#define _WIN32_WINNT 0x0400
+#define _WIN32_WINNT _WIN32_WINNT_WINXP
 #endif
 #ifndef NOUSER
 #define NOUSER
@@ -103,6 +105,20 @@
 #else
 #include <winsock.h>
 #endif
+
+/* Solve moronic tangle of defintions and dependencies from the world
+ * according to win32 api; it unconditionally declares MCAST_JOIN_SOURCE_GROUP
+ * while it declares group_source_req etc for _WIN32_WINNT_WINXP and later.
+ * Note: testing defined(GROUP_FILTER_SIZE) instead of MCAST_JOIN_SOURCE_GROUP
+ * within multicast.c would solve this connundrum.
+ *
+ * To build for mcast, define _WIN32_WINNT as _WIN32_WINNT_WINXP above.
+ */
+#if defined( MCAST_JOIN_SOURCE_GROUP ) \
+        && ( _WIN32_WINNT < 0x0501 /*_WIN32_WINNT_WINXP*/ )
+#undef MCAST_JOIN_SOURCE_GROUP 
+#endif
+
 #endif /* !_WINDOWS_ */
 
 /**
@@ -217,7 +233,7 @@
 #define APR_HAVE_IN_ADDR        1
 #define APR_HAVE_INET_ADDR      1
 #define APR_HAVE_INET_NETWORK   0
-#define APR_HAVE_IPV6           0
+#define APR_HAVE_IPV6           1
 #define APR_HAVE_MEMMOVE        1
 #define APR_HAVE_SETRLIMIT      0
 #define APR_HAVE_SIGACTION      0