--- a/openpgm/pgm/configure.ac
+++ b/openpgm/pgm/configure.ac
@@ -197,7 +197,11 @@ AC_MSG_CHECKING([for struct group_req.gr
 AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM([[#include <netinet/in.h>]],
 		[[struct group_req gr;
-gr.gr_interface = 0;]])],
+gr.gr_interface = 0;
+#ifndef MCAST_JOIN_GROUP
+# error no mcast
+#endif
+]])],
 	[AC_MSG_RESULT([yes])
 		CFLAGS="$CFLAGS -DCONFIG_HAVE_MCAST_JOIN"],
 	[AC_MSG_RESULT([no])])