diff --git a/libc/include/wchar.h b/libc/include/wchar.h
index e86f94d..56594dc 100644
--- a/libc/include/wchar.h
+++ b/libc/include/wchar.h
@@ -75,7 +75,11 @@
 wchar_t* _Nonnull wcpncpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 size_t wcrtomb(char* _Nullable __buf, wchar_t __wc, mbstate_t* _Nullable __ps);
 int wcscasecmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int wcscasecmp_l(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, locale_t _Nonnull __l) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 wchar_t* _Nonnull wcscat(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src);
 wchar_t* _Nullable wcschr(const wchar_t * _Nonnull __s, wchar_t __wc);
 int wcscmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs);
@@ -83,10 +87,18 @@
 wchar_t* _Nonnull wcscpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src);
 size_t wcscspn(const wchar_t* _Nonnull __s, const wchar_t* _Nonnull __accept);
 size_t wcsftime(wchar_t* _Nonnull __buf, size_t __n, const wchar_t* _Nullable __fmt, const struct tm* _Nonnull __tm);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 size_t wcsftime_l(wchar_t* _Nonnull __buf, size_t __n, const wchar_t* _Nullable __fmt, const struct tm* _Nonnull __tm, locale_t _Nonnull __l) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 size_t wcslen(const wchar_t* _Nonnull __s);
 int wcsncasecmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, size_t __n);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int wcsncasecmp_l(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, size_t __n, locale_t _Nonnull __l) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 wchar_t* _Nonnull wcsncat(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 int wcsncmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, size_t __n);
 wchar_t* _Nonnull wcsncpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
@@ -117,7 +129,11 @@
 int wmemcmp(const wchar_t* _Nullable __lhs, const wchar_t* _Nullable __rhs, size_t __n);
 wchar_t* _Nonnull wmemcpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 wchar_t* _Nonnull wmempcpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 #endif
 wchar_t* _Nonnull wmemmove(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 wchar_t* _Nonnull wmemset(wchar_t* _Nonnull __dst, wchar_t __wc, size_t __n);
@@ -133,7 +149,11 @@
 size_t wcslcat(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 size_t wcslcpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 FILE* _Nullable open_wmemstream(wchar_t* _Nonnull * _Nonnull __ptr, size_t* _Nonnull  __size_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 wchar_t* _Nullable wcsdup(const wchar_t* _Nonnull __s);
 size_t wcsnlen(const wchar_t* _Nonnull __s, size_t __n);