Index: sysdep/bsd/sysio.h
--- sysdep/bsd/sysio.h.orig
+++ sysdep/bsd/sysio.h
@@ -299,7 +299,7 @@ sk_dump_ao_keys(sock *s UNUSED, struct dump_request *d
 #define TCP_SIG_SPI 0x1000
 #endif
 
-#if defined(__FreeBSD__)
+#if defined(__FreeBSD__) || defined(__OpenBSD__)
 #define USE_MD5SIG_SETKEY
 #include "sysdep/bsd/setkey.h"
 #endif
