diff --git a/config.h.in b/config.h.in
index c2cb3ec1dc..5368d6824e 100644
--- a/config.h.in
+++ b/config.h.in
@@ -165,6 +165,10 @@
 #ifndef HAVE_IPPROTO_IPV6
 #define IPPROTO_IPV6 41
 #endif
+#cmakedefine HAVE_IPPROTO_IPV4
+#ifndef HAVE_IPPROTO_IPV4
+#define IPPROTO_IPV4 4
+#endif
 #cmakedefine HAVE_IPPROTO_ROUTING
 #ifndef HAVE_IPPROTO_ROUTING
 #define IPPROTO_ROUTING 43