Index: sfkext.cpp
--- sfkext.cpp.orig
+++ sfkext.cpp
@@ -488,7 +488,7 @@ int UDPIO::initSendReceive
       memset(&mreq, 0, sizeof(mreq));
       mreq.imr_interface.s_addr = htonl(INADDR_ANY);
 
-      #if defined(MAC_OS_X) || defined(SOLARIS)
+      #if defined(MAC_OS_X) || defined(SOLARIS) || defined(OPENBSD)
         #define SOL_IP IPPROTO_IP
       #endif
 
