--- a/openpgm/pgm/configure.ac
+++ b/openpgm/pgm/configure.ac
@@ -219,7 +219,11 @@ 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 -DHAVE_STRUCT_GROUP_REQ"],
 	[AC_MSG_RESULT([no])])