diff --git a/sysdep/bsd/sysio.h b/sysdep/bsd/sysio.h
index 9fc58486..b6b42b1e 100644
--- a/sysdep/bsd/sysio.h
+++ b/sysdep/bsd/sysio.h
@@ -15,9 +15,23 @@
 #ifdef __FreeBSD__
 /* Should be defined in sysdep/cf/bsd.h, but it is flavor-specific */
 #define CONFIG_DONTROUTE_UNICAST
+
+#if __FreeBSD_version >= 1201000
 #define CONFIG_USE_IP_MREQN
 #endif
 
+#endif
+
+
+#ifdef __OpenBSD__
+
+#if OpenBSD >= 202105
+#define CONFIG_USE_IP_MREQN
+#endif
+
+#endif
+
+
 #ifdef __NetBSD__
 
 #ifndef IP_RECVTTL
@@ -30,6 +44,7 @@
 
 #endif
 
+
 #ifdef __DragonFly__
 #define TCP_MD5SIG	TCP_SIGNATURE_ENABLE
 #endif