diff --git a/lib/roken/roken.h.in b/lib/roken/roken.h.in
index 19b38c325..b6bc73790 100644
--- a/lib/roken/roken.h.in
+++ b/lib/roken/roken.h.in
@@ -245,6 +245,11 @@ extern int h_errno;
 int inet_aton(const char *cp, struct in_addr *adr);
 #endif
 
+#ifndef HAVE_INET_NTOP
+const char *
+inet_ntop(int af, const void *src, char *dst, size_t size);
+#endif
+
 #if !defined(HAVE_GETCWD)
 char* getcwd(char *path, size_t size);
 #endif