diff --git a/0001-Fix-Bytes-String-for-OCaml-4.06.patch b/0001-Fix-Bytes-String-for-OCaml-4.06.patch
deleted file mode 100644
index 4d1408a..0000000
--- a/0001-Fix-Bytes-String-for-OCaml-4.06.patch
+++ /dev/null
@@ -1,58 +0,0 @@
-From 5c5eff66dfaccb212b8906e769e40633d8b8f5e4 Mon Sep 17 00:00:00 2001
-From: "Richard W.M. Jones" <rjones@redhat.com>
-Date: Tue, 13 Feb 2018 08:20:52 +0000
-Subject: [PATCH] Fix Bytes/String for OCaml 4.06.
-
----
- src/format_ext2_kernel.ml |  4 ++--
- src/mode_build.ml         | 10 ++++++----
- 2 files changed, 8 insertions(+), 6 deletions(-)
-
-diff --git a/src/format_ext2_kernel.ml b/src/format_ext2_kernel.ml
-index d5d529d..98bff3a 100644
---- a/src/format_ext2_kernel.ml
-+++ b/src/format_ext2_kernel.ml
-@@ -290,9 +290,9 @@ and read_leshort chan offset =
- 
- and read_string chan offset len =
-   seek_in chan offset;
--  let buf = String.create len in
-+  let buf = Bytes.create len in
-   really_input chan buf 0 len;
--  buf
-+  Bytes.to_string buf
- 
- and copy_or_symlink_file copy_kernel src dest =
-   if not copy_kernel then
-diff --git a/src/mode_build.ml b/src/mode_build.ml
-index 95869cb..b5f5fa6 100644
---- a/src/mode_build.ml
-+++ b/src/mode_build.ml
-@@ -299,9 +299,10 @@ and update_appliance appliance lines = function
- (* Determine the [file_type] of [file], or exit with an error. *)
- and get_file_type file =
-   let chan = open_in file in
--  let buf = String.create 512 in
--  let len = input chan buf 0 (String.length buf) in
-+  let buf = Bytes.create 512 in
-+  let len = input chan buf 0 (Bytes.length buf) in
-   close_in chan;
-+  let buf = Bytes.to_string buf in
- 
-   if len >= 3 && buf.[0] = '\x1f' && buf.[1] = '\x8b' && buf.[2] = '\x08'
-   then                                  (* gzip-compressed file *)
-@@ -335,8 +336,9 @@ and get_file_content file buf len =
- and get_compressed_file_content zcat file =
-   let cmd = sprintf "%s %s" zcat (quote file) in
-   let chan_out, chan_in, chan_err = open_process_full cmd [||] in
--  let buf = String.create 512 in
--  let len = input chan_out buf 0 (String.length buf) in
-+  let buf = Bytes.create 512 in
-+  let len = input chan_out buf 0 (Bytes.length buf) in
-+  let buf = Bytes.to_string buf in
-   (* We're expecting the subprocess to fail because we close the pipe
-    * early, so:
-    *)
--- 
-2.15.1
-
diff --git a/sources b/sources
index 9b748f8..d77c08a 100644
--- a/sources
+++ b/sources
@@ -1,2 +1,2 @@
-SHA512 (supermin-5.1.19.tar.gz) = 31098d419425b0229e5c6287bcaf40942d74c950f17c4656f060042eb665676057823196cbce252d11989f86ec2d9c171d0c5f942817809723f6efc447f1529b
-SHA512 (supermin-5.1.19.tar.gz.sig) = c49d891f8b95878e262cba8d1a23855467f1231ce018d5159583adb2fa1ff30c02cab50c3afa05b3adcc1cdc111cb3bb42e6123202d2d804d0d79eb590625eec
+SHA512 (supermin-5.1.20.tar.gz) = ccc9ada98593f91399b323f0beb027185874f82547a1df4274c1206a9b6d4465e98b7aef5618274d41fb902747f6843fd2cc6192a4ea8526811261ac5a16848e
+SHA512 (supermin-5.1.20.tar.gz.sig) = e7c46fdf4105ffa3f6e02d6ed0b895a9af71470f5c650d129304187b977516343d17a861a9c53934eee559de374623f100f4736426de37ee78d5f5bc82d56096
diff --git a/supermin.spec b/supermin.spec
index 47d712a..fd80f75 100644
--- a/supermin.spec
+++ b/supermin.spec
@@ -25,8 +25,8 @@
 
 Summary:       Tool for creating supermin appliances
 Name:          supermin
-Version:       5.1.19
-Release:       5%{?dist}
+Version:       5.1.20
+Release:       1%{?dist}
 License:       GPLv2+
 
 %if 0%{?rhel} >= 7
@@ -44,9 +44,6 @@ Source1:       http://libguestfs.org/download/supermin/%{name}-%{version}.tar.gz
 Source2:       libguestfs.keyring
 %endif
 
-# Upstream patch which fixes byte/string problems.
-Patch1:        0001-Fix-Bytes-String-for-OCaml-4.06.patch
-
 BuildRequires: /usr/bin/pod2man
 BuildRequires: /usr/bin/pod2html
 BuildRequires: rpm
@@ -168,6 +165,9 @@ make check || {
 
 
 %changelog
+* Thu Jan 17 2019 Richard W.M. Jones <rjones@redhat.com> - 5.1.20-1
+- New upstream version 5.1.20.
+
 * Sat Jul 14 2018 Fedora Release Engineering <releng@fedoraproject.org> - 5.1.19-5
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_29_Mass_Rebuild