diff --git a/SOURCES/0001-Please-make-the-output-reproducible.patch b/SOURCES/0001-Please-make-the-output-reproducible.patch
new file mode 100644
index 0000000..ba0f0de
--- /dev/null
+++ b/SOURCES/0001-Please-make-the-output-reproducible.patch
@@ -0,0 +1,54 @@
+From 06eda7ca8fa42c654fd2ad861c1c43c1b395bc57 Mon Sep 17 00:00:00 2001
+From: Chris Lamb <lamby@debian.org>
+Date: Sat, 7 Dec 2019 13:56:24 +0000
+Subject: [PATCH] Please make the output reproducible
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Whilst working on the Reproducible Builds effort [0] we noticed that
+gtk-doc generates unreproducible output.
+
+There will likely be more issues but this one is at least fairly
+simple in that it iterates over a set structure when printing
+some .devhelp2 headers, for example:
+
+│ │ │ │ -    <sub name="Index of new API in 0.99.5" link="api-index-0-99-5.html"/>
+│ │ │ │ -    <sub name="Index of new API in 0.9.22" link="api-index-0-9-22.html"/>
+│ │ │ │      <sub name="Index of new API in 0.9.0" link="api-index-0-9-0.html"/>
+│ │ │ │ -    <sub name="Index of new API in 0.9.1" link="api-index-0-9-1.html"/>
+│ │ │ │ +    <sub name="Index of new API in 0.9.19" link="api-index-0-9-19.html"/>
+│ │ │ │      <sub name="Index of new API in 0.99.8" link="api-index-0-99-8.html"/>
+│ │ │ │ +    <sub name="Index of new API in 0.99.5" link="api-index-0-99-5.html"/>
+│ │ │ │      <sub name="Index of new API in 1.0" link="api-index-1-0.html"/>
+│ │ │ │ -    <sub name="Index of new API in 0.9.19" link="api-index-0-9-19.html"/>
+│ │ │ │      <sub name="Index of new API in 0.9.2" link="api-index-0-9-2.html"/>
+│ │ │ │ +    <sub name="Index of new API in 0.9.1" link="api-index-0-9-1.html"/>
+│ │ │ │ +    <sub name="Index of new API in 0.9.22" link="api-index-0-9-22.html"/>
+
+This was originally filed in Debian as #946311 [1].
+
+ [0] https://reproducible-builds.org/
+ [1] https://bugs.debian.org/946331
+
+Signed-off-by: Chris Lamb <lamby@debian.org>
+---
+ gtkdoc/mkdb.py | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/gtkdoc/mkdb.py b/gtkdoc/mkdb.py
+index 9404452..9184567 100644
+--- a/gtkdoc/mkdb.py
++++ b/gtkdoc/mkdb.py
+@@ -2491,7 +2491,7 @@ def OutputBook(main_file, book_top, book_bottom, obj_tree):
+     <xi:include href="xml/api-index-deprecated.xml"><xi:fallback /></xi:include>
+   </index>
+ ''')
+-        for version in set(Since.values()):
++        for version in sorted(set(Since.values())):
+             dash_version = version.replace('.', '-')
+             OUTPUT.write('''  <index id="api-index-%s" role="%s">
+     <title>Index of new API in %s</title>
+-- 
+2.26.2
+
diff --git a/SPECS/gtk-doc.spec b/SPECS/gtk-doc.spec
index e6337de..17cbc16 100644
--- a/SPECS/gtk-doc.spec
+++ b/SPECS/gtk-doc.spec
@@ -4,13 +4,17 @@
 
 Name: gtk-doc
 Version: 1.28
-Release: 1%{?dist}
+Release: 2%{?dist}
 Summary: API documentation generation tool for GTK+ and GNOME
 
 License: GPLv2+ and GFDL
 URL: http://www.gtk.org/gtk-doc
 Source0: http://download.gnome.org/sources/gtk-doc/1.28/gtk-doc-%{version}.tar.xz
 
+# Backported from upstream
+# https://bugzilla.redhat.com/show_bug.cgi?id=1634770
+Patch0: 0001-Please-make-the-output-reproducible.patch
+
 BuildRequires: dblatex
 BuildRequires: docbook-utils
 BuildRequires: /usr/bin/xsltproc
@@ -61,6 +65,10 @@ make check || make check
 %{_libdir}/cmake/
 
 %changelog
+* Mon Jul 20 2020 Kalev Lember <klember@redhat.com> - 1.28-2
+- Backport a patch to fix x86_64/i686 differences in generated documentation
+- Resolves: #1634770
+
 * Sat Mar 24 2018 Kalev Lember <klember@redhat.com> - 1.28-1
 - Update to 1.28
 - Switch to Python 3 (#1509660)