diff --git a/libc/include/netdb.h b/libc/include/netdb.h
index 88214d5..04aaf5c 100644
--- a/libc/include/netdb.h
+++ b/libc/include/netdb.h
@@ -212,28 +212,52 @@
 void herror(const char* _Nonnull __s);
 const char* _Nonnull hstrerror(int __error);
 struct hostent* _Nullable gethostbyaddr(const void* _Nonnull __addr, socklen_t __length, int __type);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int gethostbyaddr_r(const void* _Nonnull __addr, socklen_t __length, int __type, struct hostent* _Nonnull __ret, char* _Nonnull __buf, size_t __buf_size, struct hostent* _Nullable * _Nonnull __result, int* _Nonnull __h_errno_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 struct hostent* _Nullable gethostbyname(const char* _Nonnull __name);
 int gethostbyname_r(const char* _Nonnull __name, struct hostent* _Nonnull __ret, char* _Nonnull __buf, size_t __buf_size, struct hostent* _Nullable * _Nonnull __result, int* _Nonnull __h_errno_ptr);
 struct hostent* _Nullable gethostbyname2(const char* _Nonnull __name, int __af);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int gethostbyname2_r(const char* _Nonnull __name, int __af, struct hostent* _Nonnull __ret, char* _Nonnull __buf, size_t __buf_size, struct hostent* _Nullable * _Nonnull __result, int* _Nonnull __h_errno_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 void endhostent(void) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 struct hostent* _Nullable gethostent(void);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 void sethostent(int __stay_open) __INTRODUCED_IN(28);
 
 /* These functions are obsolete. None of these functions return anything but nullptr. */
 void endnetent(void) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 struct netent* _Nullable getnetbyaddr(uint32_t __net, int __type);
 struct netent* _Nullable getnetbyname(const char* _Nonnull __name);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 struct netent* _Nullable getnetent(void) __INTRODUCED_IN(28);
 void setnetent(int __stay_open) __INTRODUCED_IN(28);
 
 /* None of these functions return anything but nullptr. */
 void endprotoent(void) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 struct protoent* _Nullable getprotobyname(const char* _Nonnull __name);
 struct protoent* _Nullable getprotobynumber(int __proto);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 struct protoent* _Nullable getprotoent(void) __INTRODUCED_IN(28);
 void setprotoent(int __stay_open) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 /* These functions return entries from a built-in database. */
 void endservent(void);