diff --git a/meta-arm-bsp/recipes-bsp/uefi/edk2-firmware_202408.bb b/meta-arm-bsp/recipes-bsp/uefi/edk2-firmware_202408.bb
index ea03d47b..fa44e28f 100644
--- a/meta-arm-bsp/recipes-bsp/uefi/edk2-firmware_202408.bb
+++ b/meta-arm-bsp/recipes-bsp/uefi/edk2-firmware_202408.bb
@@ -1,9 +1,12 @@
 SRCREV_edk2           ?= "b158dad150bf02879668f72ce306445250838201"
 SRCREV_edk2-platforms ?= "a3c898956a4d48dc5980336fa6ce6eeb23c4f72b"
 
-SRC_URI += "file://0001-Platform-StMmRpmb-Fix-build.patch;patchdir=edk2-platforms"
+SRC_URI += "file://0001-Platform-StMmRpmb-Fix-build.patch;patchdir=edk2-platforms \
+            file://0001-BaseTools-Pccts-set-C-standard.patch"
 
-# FIXME - clang is having issues with antlr
+# FIXME:
+# ArmPkg/Universal/Smbios/SmbiosMiscDxe/Type03/MiscChassisManufacturerFunction.c:146:37:
+# error: variable 'ContainedElements' is uninitialized when passed as a const pointer argument here [-Werror,-Wuninitialized-const-pointer]
 TOOLCHAIN:aarch64 = "gcc"
 
 require recipes-bsp/uefi/edk2-firmware.inc
diff --git a/meta-arm-bsp/recipes-bsp/uefi/files/0001-BaseTools-Pccts-set-C-standard.patch b/meta-arm-bsp/recipes-bsp/uefi/files/0001-BaseTools-Pccts-set-C-standard.patch
new file mode 100644
index 00000000..058073c9
--- /dev/null
+++ b/meta-arm-bsp/recipes-bsp/uefi/files/0001-BaseTools-Pccts-set-C-standard.patch
@@ -0,0 +1,47 @@
+From e063f8b8a53861043b9872cc35b08a3dc03b0942 Mon Sep 17 00:00:00 2001
+From: Gerd Hoffmann <kraxel@redhat.com>
+Date: Mon, 20 Jan 2025 09:40:31 +0100
+Subject: [PATCH] BaseTools/Pccts: set C standard
+
+The prehistoric code base doesn't build with ISO C23.  Set the C
+standard to C11 (for both clang and gcc) so it continues to build with
+gcc 15 (which uses C23 by default).
+
+Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
+
+Upstream-Status: Backport [e063f8b8a53861043b9872cc35b08a3dc03b0942]
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+---
+ BaseTools/Source/C/VfrCompile/Pccts/antlr/makefile | 2 +-
+ BaseTools/Source/C/VfrCompile/Pccts/dlg/makefile   | 2 +-
+ 2 files changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/BaseTools/Source/C/VfrCompile/Pccts/antlr/makefile b/BaseTools/Source/C/VfrCompile/Pccts/antlr/makefile
+index 746d58b5e2..b47c8a37af 100644
+--- a/BaseTools/Source/C/VfrCompile/Pccts/antlr/makefile
++++ b/BaseTools/Source/C/VfrCompile/Pccts/antlr/makefile
+@@ -169,7 +169,7 @@ ANTLR=${BIN_DIR}/antlr
+ DLG=${BIN_DIR}/dlg
+ OBJ_EXT=o
+ OUT_OBJ = -o
+-CFLAGS= $(COPT) -I. -I$(SET) -I$(PCCTS_H) -DUSER_ZZSYN $(COTHER) -DZZLEXBUFSIZE=65536
++CFLAGS= $(COPT) -I. -I$(SET) -I$(PCCTS_H) -DUSER_ZZSYN $(COTHER) -DZZLEXBUFSIZE=65536 -std=gnu11
+ CPPFLAGS=
+ #
+ # SGI Users, use this CFLAGS
+diff --git a/BaseTools/Source/C/VfrCompile/Pccts/dlg/makefile b/BaseTools/Source/C/VfrCompile/Pccts/dlg/makefile
+index e45ac98e04..d72bee3d70 100644
+--- a/BaseTools/Source/C/VfrCompile/Pccts/dlg/makefile
++++ b/BaseTools/Source/C/VfrCompile/Pccts/dlg/makefile
+@@ -123,7 +123,7 @@ endif
+ COPT=-O
+ ANTLR=${BIN_DIR}/antlr
+ DLG=${BIN_DIR}/dlg
+-CFLAGS= $(COPT) -I. -I$(SET) -I$(PCCTS_H) -DUSER_ZZSYN -DZZLEXBUFSIZE=65536
++CFLAGS= $(COPT) -I. -I$(SET) -I$(PCCTS_H) -DUSER_ZZSYN -DZZLEXBUFSIZE=65536 -std=gnu11
+ CPPFLAGS=
+ OBJ_EXT=o
+ OUT_OBJ = -o
+-- 
+2.43.0
+