diff --git a/0001-Use-ocamlopt-g-option.patch b/0001-Use-ocamlopt-g-option.patch
index f263e30..be46e09 100644
--- a/0001-Use-ocamlopt-g-option.patch
+++ b/0001-Use-ocamlopt-g-option.patch
@@ -1,7 +1,7 @@
 From 56c0602e972f1fae336198eb9587d71f1e36daff Mon Sep 17 00:00:00 2001
 From: "Richard W.M. Jones" <rjones@redhat.com>
 Date: Tue, 20 Aug 2019 15:06:57 +0100
-Subject: [PATCH] Use ocamlopt -g option.
+Subject: [PATCH 1/2] Use ocamlopt -g option.
 
 Originally from Fedora.
 ---
@@ -24,5 +24,5 @@ index e01385f..4ae5ef5 100644
  OCAMLDOCFLAGS	= -html -sort
  
 -- 
-2.22.0
+2.23.0
 
diff --git a/0002-caml_named_value-returns-const-value-pointer-in-OCam.patch b/0002-caml_named_value-returns-const-value-pointer-in-OCam.patch
new file mode 100644
index 0000000..22c5ed9
--- /dev/null
+++ b/0002-caml_named_value-returns-const-value-pointer-in-OCam.patch
@@ -0,0 +1,35 @@
+From 1cf5aef99b26a46529ca797547c0b49627fffe78 Mon Sep 17 00:00:00 2001
+From: "Richard W.M. Jones" <rjones@redhat.com>
+Date: Sat, 7 Dec 2019 11:08:54 +0000
+Subject: [PATCH 2/2] caml_named_value returns const value pointer in OCaml
+ 4.09+
+
+---
+ augeas-c.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/augeas-c.c b/augeas-c.c
+index 9217017..679bcb5 100644
+--- a/augeas-c.c
++++ b/augeas-c.c
+@@ -86,7 +86,7 @@ static const int error_map_len = sizeof error_map / sizeof error_map[0];
+ static void
+ raise_error_and_maybe_close (augeas_t t, const char *msg, bool close_handle)
+ {
+-  value *exn = caml_named_value ("Augeas.Error");
++  const value *exn = caml_named_value ("Augeas.Error");
+   value args[5];
+   const int code = aug_error (t);
+   const char *aug_err_msg;
+@@ -132,7 +132,7 @@ raise_error_and_maybe_close (augeas_t t, const char *msg, bool close_handle)
+ static void
+ raise_init_error (const char *msg)
+ {
+-  value *exn = caml_named_value ("Augeas.Error");
++  const value *exn = caml_named_value ("Augeas.Error");
+   value args[5];
+ 
+   args[0] = caml_alloc (1, 0);
+-- 
+2.23.0
+
diff --git a/ocaml-augeas.spec b/ocaml-augeas.spec
index 19ceb57..842b061 100644
--- a/ocaml-augeas.spec
+++ b/ocaml-augeas.spec
@@ -11,6 +11,8 @@ Source0:        http://people.redhat.com/~rjones/augeas/files/%{name}-%{version}
 
 # Upstream patch to enable debuginfo.
 Patch1:         0001-Use-ocamlopt-g-option.patch
+# Const-correctness fix for OCaml 4.09+
+Patch2:         0002-caml_named_value-returns-const-value-pointer-in-OCam.patch
 
 BuildRequires:  ocaml >= 3.09.0
 BuildRequires:  ocaml-findlib-devel
@@ -95,6 +97,7 @@ chrpath --delete $OCAMLFIND_DESTDIR/stublibs/dll*.so
 %changelog
 * Fri Dec 06 2019 Richard W.M. Jones <rjones@redhat.com> - 0.6-2
 - OCaml 4.09.0 (final) rebuild.
+- Add upstream const-correctness build fix.
 
 * Tue Aug 20 2019 Richard W.M. Jones <rjones@redhat.com> - 0.6-1
 - New upstream version 0.6.