diff --git a/io.c b/io.c
index 5412639..095da32 100644
--- a/io.c
+++ b/io.c
@@ -2087,6 +2087,11 @@ io_setstrbuf(VALUE *str,long len)
     rb_str_modify_expand(*str, len);
 }
 
+static VALUE sym_sequential;
+#if defined(HAVE_POSIX_FADVISE) && defined(POSIX_FADV_SEQUENTIAL)
+static VALUE do_io_advise(rb_io_t *fptr, VALUE advice, off_t offset, off_t len);
+#endif
+
 static VALUE
 read_all(rb_io_t *fptr, long siz, VALUE str)
 {
@@ -2096,6 +2101,10 @@ read_all(rb_io_t *fptr, long siz, VALUE str)
     rb_encoding *enc;
     int cr;
 
+#if defined(HAVE_POSIX_FADVISE) && defined(POSIX_FADV_SEQUENTIAL)
+    do_io_advise(fptr, sym_sequential, (off_t)0LL, (off_t)0LL);
+#endif
+
     if (NEED_READCONV(fptr)) {
 	SET_BINARY_MODE(fptr);
 	io_setstrbuf(&str,0);
@@ -7875,7 +7884,7 @@ select_end(VALUE arg)
     return Qnil;
 }
 
-static VALUE sym_normal,   sym_sequential, sym_random,
+static VALUE sym_normal, sym_random,
              sym_willneed, sym_dontneed, sym_noreuse;
 
 #ifdef HAVE_POSIX_FADVISE