diff --git a/meta-xfce/recipes-xfce/xfce4-panel/files/0001-panel-tic-tac-toe-Remove-wrong-autoptr-define-guard.patch b/meta-xfce/recipes-xfce/xfce4-panel/files/0001-panel-tic-tac-toe-Remove-wrong-autoptr-define-guard.patch
new file mode 100644
index 0000000000..493e468bc4
--- /dev/null
+++ b/meta-xfce/recipes-xfce/xfce4-panel/files/0001-panel-tic-tac-toe-Remove-wrong-autoptr-define-guard.patch
@@ -0,0 +1,42 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Mon, 23 Jun 2026 00:00:00 +0000
+Subject: [PATCH] panel: tic-tac-toe: Remove wrong autoptr define guard
+
+panel-tic-tac-toe.h guarded its own
+G_DEFINE_AUTOPTR_CLEANUP_FUNC (XfceTitledDialog, g_object_unref) with
+"#ifndef glib_autoptr_clear_XfceTitledDialog". That macro is never
+defined: G_DEFINE_AUTOPTR_CLEANUP_FUNC emits static inline functions, not
+a glib_autoptr_clear_* macro, so the guard is always true.
+
+libxfce4ui (>= 4.21.8) now defines the XfceTitledDialog autoptr cleanup
+functions itself in xfce-titled-dialog.h. Because the guard never
+triggers, the panel header redefines the same static inline cleanup
+functions, which is a hard error with GCC 16 / recent clang:
+
+  error: redefinition of 'glib_autoptr_clear_XfceTitledDialog'
+
+Drop the redundant definition entirely; rely on libxfce4ui to provide it.
+
+Upstream-Status: Backport [https://gitlab.xfce.org/xfce/xfce4-panel/-/commit/3ac941fc083fee5e56b0f3e509d6f6b461b48e39]
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+---
+ panel/panel-tic-tac-toe.h | 3 ---
+ 1 file changed, 3 deletions(-)
+
+diff --git a/panel/panel-tic-tac-toe.h b/panel/panel-tic-tac-toe.h
+index 1111111..2222222 100644
+--- a/panel/panel-tic-tac-toe.h
++++ b/panel/panel-tic-tac-toe.h
+@@ -24,9 +24,6 @@ G_BEGIN_DECLS
+ G_BEGIN_DECLS
+
+ #define PANEL_TYPE_TIC_TAC_TOE (panel_tic_tac_toe_get_type ())
+-#ifndef glib_autoptr_clear_XfceTitledDialog
+-G_DEFINE_AUTOPTR_CLEANUP_FUNC (XfceTitledDialog, g_object_unref)
+-#endif
+ G_DECLARE_FINAL_TYPE (PanelTicTacToe, panel_tic_tac_toe, PANEL, TIC_TAC_TOE, XfceTitledDialog)
+
+ void
+-- 
+2.43.0
diff --git a/meta-xfce/recipes-xfce/xfce4-panel/xfce4-panel_4.21.1.bb b/meta-xfce/recipes-xfce/xfce4-panel/xfce4-panel_4.21.1.bb
index 350784e083..1998a9f23e 100644
--- a/meta-xfce/recipes-xfce/xfce4-panel/xfce4-panel_4.21.1.bb
+++ b/meta-xfce/recipes-xfce/xfce4-panel/xfce4-panel_4.21.1.bb
@@ -17,6 +17,7 @@ SRC_URI += " \
     file://0001-build-Do-not-display-full-path-in-generated-headers.patch \
     file://0001-build-Be-sure-to-generate-sub-headers-before-includi.patch \
     file://0002-build-Install-missing-libxfce4panel.h.patch \
+    file://0001-panel-tic-tac-toe-Remove-wrong-autoptr-define-guard.patch \
 "
 SRC_URI[sha256sum] = "c940dae515bef4af08a126011d2fd873ce99e815157ba8cef5332195bb60e51e"