diff --git a/0001-Safe-string-support.patch b/0001-Safe-string-support.patch
new file mode 100644
index 0000000..6385f28
--- /dev/null
+++ b/0001-Safe-string-support.patch
@@ -0,0 +1,30 @@
+From 84ffcbebb71293e419154b0093cfc81f64e885fa Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Daniel=20B=C3=BCnzli?= <daniel.buenzli@erratique.ch>
+Date: Wed, 15 Mar 2017 23:37:03 +0100
+Subject: [PATCH] Safe-string support.
+
+(cherry picked from commit 0e29ed18ce6617a45de478cde07db4c1625c5a64)
+---
+ _tags       | 2 +-
+ opam        | 2 +-
+ src/xmlm.ml | 4 ++--
+ 3 files changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/src/xmlm.ml b/src/xmlm.ml
+index 1bb8bbc..c97501a 100644
+--- a/src/xmlm.ml
++++ b/src/xmlm.ml
+@@ -960,8 +960,8 @@ struct
+     
+   let make_output ?(decl = true) ?(nl = false) ?(indent = None) 
+       ?(ns_prefix = fun _ ->None) d =
+-    let outs, outc = match d with 
+-    | `Channel c -> (output c), (output_char c)
++    let outs, outc = match d with
++    | `Channel c -> (output_substring c), (output_char c)
+     | `Buffer b -> (Std_buffer.add_substring b), (Std_buffer.add_char b)
+     | `Fun f -> 
+         let os s p l = 
+-- 
+2.13.1
+
diff --git a/ocaml-xmlm.spec b/ocaml-xmlm.spec
index c0aab91..ff31251 100644
--- a/ocaml-xmlm.spec
+++ b/ocaml-xmlm.spec
@@ -11,12 +11,17 @@ Summary:        A streaming XML codec
 License:        BSD
 URL:            http://erratique.ch/software/xmlm
 Source0:        http://erratique.ch/software/xmlm/releases/xmlm-%{version}.tbz
-# Ensure source files are included in generated debuginfo subpackage
-Patch0:         xmlm-1.2.0-debug.patch
+
 # Example XML files for testing
 Source1:        test-valid.xml
 Source2:        test-invalid.xml
 
+# Ensure source files are included in generated debuginfo subpackage
+Patch0:         xmlm-1.2.0-debug.patch
+
+# Safe-string, cherry-picked from upstream.
+Patch1:         0001-Safe-string-support.patch
+
 BuildRequires:  ocaml >= 3.10.0
 BuildRequires:  ocaml-findlib
 BuildRequires:  ocaml-ocamlbuild
@@ -41,6 +46,7 @@ developing applications that use %{name}.
 %prep
 %setup -q -n %{libname}-%{version}
 %patch0 -p1 -b .debug
+%patch1 -p1
 
 
 %build
@@ -104,8 +110,9 @@ grep expected invalid-err.log >/dev/null
 
 
 %changelog
-* Sat Nov 18 2017 Richard W.M. Jones <rjones@redhat.com> - 1.2.0-25
+* Wed Nov 22 2017 Richard W.M. Jones <rjones@redhat.com> - 1.2.0-25
 - OCaml 4.06.0 rebuild.
+- Fix safe-string for OCaml 4.06.
 
 * Wed Aug 09 2017 Richard W.M. Jones <rjones@redhat.com> - 1.2.0-24
 - OCaml 4.05.0 rebuild.