diff --git a/src/os/unix/ngx_files.c b/src/os/unix/ngx_files.c
index ad26d2752..196323727 100644
--- a/src/os/unix/ngx_files.c
+++ b/src/os/unix/ngx_files.c
@@ -464,7 +464,7 @@ ngx_unlock_fd(ngx_fd_t fd)
 }
 
 
-#if (NGX_HAVE_POSIX_FADVISE)
+#if (NGX_HAVE_POSIX_FADVISE) && !(NGX_HAVE_F_READAHEAD)
 
 ngx_int_t
 ngx_read_ahead(ngx_fd_t fd, size_t n)