diff --git a/pyglet-1.5.16-backport-pr-469.patch b/pyglet-1.5.16-backport-pr-469.patch
new file mode 100644
index 0000000..e2ef360
--- /dev/null
+++ b/pyglet-1.5.16-backport-pr-469.patch
@@ -0,0 +1,21 @@
+diff -Naur pyglet-1.5.16-original/tests/unit/media/test_synthesis.py pyglet-1.5.16/tests/unit/media/test_synthesis.py
+--- pyglet-1.5.16-original/tests/unit/media/test_synthesis.py	2021-04-13 05:57:56.000000000 -0400
++++ pyglet-1.5.16/tests/unit/media/test_synthesis.py	2021-10-10 14:46:08.063474857 -0400
+@@ -1,4 +1,5 @@
+ import unittest
++import wave
+ 
+ from ctypes import sizeof
+ from io import BytesIO
+@@ -79,9 +80,8 @@
+         source_name = self.source_class.__name__.lower()
+         filename = "synthesis_{0}_{1}_{2}_1ch.wav".format(source_name, sample_size, sample_rate)
+ 
+-        with open(get_test_data_file('media', filename), 'rb') as f:
+-            # discard the wave header:
+-            loaded_bytes = f.read()[44:]
++        with wave.open(get_test_data_file('media', filename)) as f:
++            loaded_bytes = f.readframes(-1)
+             source.seek(0)
+             generated_data = source.get_audio_data(source._max_offset)
+             bytes_buffer = BytesIO(generated_data.data).getvalue()
diff --git a/python-pyglet.spec b/python-pyglet.spec
index 2ed23a8..b2efcd7 100644
--- a/python-pyglet.spec
+++ b/python-pyglet.spec
@@ -5,7 +5,7 @@
 
 Name: python-%{srcname}
 Version: 1.5.16
-Release: 3%{?dist}
+Release: 4%{?dist}
 Summary: A cross-platform windowing and multimedia library for Python
 
 License: BSD
@@ -20,6 +20,10 @@ URL: http://www.pyglet.org/
 Source0: %{versionedname}-repacked.tar.gz
 Source1: pyglet-get-tarball.sh
 
+# Backport upstream patch for big-endian support to remove ExcludeArch:
+# https://github.com/pyglet/pyglet/pull/469
+Patch0: pyglet-1.5.16-backport-pr-469.patch
+
 # Note that unbundling pypng removes "PNGImageDecoder", which is normally
 # available for advanced use cases. Instead of:
 #     img = image.load(fname, decoder=PNGImageDecoder) # don't use!
@@ -32,11 +36,6 @@ Source1: pyglet-get-tarball.sh
 
 BuildArch: noarch
 
-# Tests (and possibly sound synthesis?) fail on big-endian.
-# Reported: https://github.com/pyglet/pyglet/issues/278
-# Fedora bug: https://bugzilla.redhat.com/show_bug.cgi?id=1877849
-ExcludeArch: s390x
-
 BuildRequires: python3-devel
 BuildRequires: pyproject-rpm-macros
 
@@ -152,6 +151,9 @@ ln -s %{_datadir}/sounds/purple/*.wav tests/data/media/
 
 
 %changelog
+* Sun Oct 10 2021 Benjamin A. Beasley <code@musicinmybrain.net> - 1.5.16-4
+- Backport upstream patch to fix ExcludeArch (fix RHBZ#1877849)
+
 * Fri Jul 23 2021 Fedora Release Engineering <releng@fedoraproject.org> - 1.5.16-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_35_Mass_Rebuild