diff --git a/src/common/compat.h b/src/common/compat.h
index ad791b9bf0..cd93452268 100644
--- a/src/common/compat.h
+++ b/src/common/compat.h
@@ -283,6 +283,16 @@ struct in6_addr
 };
 #endif
 
+#if defined(__APPLE__) || defined(__darwin__)
+/* OSX seems not to define these. */
+#ifndef s6_addr16
+#define s6_addr16 __u6_addr.__u6_addr16
+#endif
+#ifndef s6_addr32
+#define s6_addr32 __u6_addr.__u6_addr32
+#endif
+#endif
+
 #if !defined(HAVE_STRUCT_SOCKADDR_IN6)
 struct sockaddr_in6 {
   uint16_t sin6_family; /* XXXX020 right size???? */