diff --git a/include/stdlib.h b/include/stdlib.h
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -111,7 +111,9 @@
 	    int (* _Nonnull)(const void *, const void *));
 int	 rand(void);
 void	*realloc(void *, size_t) __result_use_check __alloc_size(2);
+#if __BSD_VISIBLE
 char	*secure_getenv(const char *);
+#endif
 void	 srand(unsigned);
 double	 strtod(const char * __restrict, char ** __restrict);
 float	 strtof(const char * __restrict, char ** __restrict);