diff --git a/meta/recipes-graphics/piglit/piglit/0001-tests-serializer-reproducible_mtime-should-be-an-int.patch b/meta/recipes-graphics/piglit/piglit/0001-tests-serializer-reproducible_mtime-should-be-an-int.patch
new file mode 100644
index 00000000000..4578c296b0d
--- /dev/null
+++ b/meta/recipes-graphics/piglit/piglit/0001-tests-serializer-reproducible_mtime-should-be-an-int.patch
@@ -0,0 +1,33 @@
+From 58a5bea55a5f7972462124e7a8f1b1971ad5483d Mon Sep 17 00:00:00 2001
+From: Ross Burton <ross.burton@arm.com>
+Date: Thu, 22 Oct 2026 14:09:08 +0100
+Subject: [PATCH] tests/serializer: reproducible_mtime should be an int
+X-ARM-No-Footer: NoDisclaimer
+
+The mtime argument is an integer not a string, so parse it with int().
+
+Passing a string breaks piglit with Python 3.14.9, which does integer
+bound checks on the specified mtime.
+
+Upstream-Status: Submitted [https://gitlab.freedesktop.org/mesa/piglit/-/merge_requests/1269]
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+---
+ tests/serializer.py | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/tests/serializer.py b/tests/serializer.py
+index 5ee9a1578..f7fdadf43 100644
+--- a/tests/serializer.py
++++ b/tests/serializer.py
+@@ -140,7 +140,7 @@ def serializer(name, profile, outfile):
+     tree = et.ElementTree(root)
+     reproducible_mtime = None
+     if 'SOURCE_DATE_EPOCH' in os.environ:
+-        reproducible_mtime=os.environ['SOURCE_DATE_EPOCH']
++        reproducible_mtime=int(os.environ['SOURCE_DATE_EPOCH'])
+     with gzip.GzipFile(outfile, 'wb', mtime=reproducible_mtime) as f:
+         tree.write(f, encoding='utf-8', xml_declaration=True)
+ 
+-- 
+2.43.0
+
diff --git a/meta/recipes-graphics/piglit/piglit_git.bb b/meta/recipes-graphics/piglit/piglit_git.bb
index 8f02496b4fd..f25679b8290 100644
--- a/meta/recipes-graphics/piglit/piglit_git.bb
+++ b/meta/recipes-graphics/piglit/piglit_git.bb
@@ -11,6 +11,7 @@ SRC_URI = "git://gitlab.freedesktop.org/mesa/piglit.git;protocol=https;branch=ma
            file://0003-tests-util-piglit-shader.c-do-not-hardcode-build-pat.patch \
            file://0001-CMakeLists.txt-do-not-obtain-wayland-scanner-path-fr.patch \
            file://0001-tests-no_error.py-modify-_command-and-not-command.patch \
+           file://0001-tests-serializer-reproducible_mtime-should-be-an-int.patch \
            "
 UPSTREAM_CHECK_COMMITS = "1"