diff --git a/config/u-boot/gru_bob/target.cfg b/config/u-boot/gru_bob/target.cfg
index 1633e9df..f7d4d7d9 100644
--- a/config/u-boot/gru_bob/target.cfg
+++ b/config/u-boot/gru_bob/target.cfg
@@ -1,2 +1,3 @@
 tree="default"
+xtree="default"
 xarch="aarch64-elf arm-eabi"
diff --git a/config/u-boot/gru_kevin/target.cfg b/config/u-boot/gru_kevin/target.cfg
index 1633e9df..f7d4d7d9 100644
--- a/config/u-boot/gru_kevin/target.cfg
+++ b/config/u-boot/gru_kevin/target.cfg
@@ -1,2 +1,3 @@
 tree="default"
+xtree="default"
 xarch="aarch64-elf arm-eabi"
diff --git a/config/u-boot/qemu_arm64_12mb/target.cfg b/config/u-boot/qemu_arm64_12mb/target.cfg
index 1633e9df..f7d4d7d9 100644
--- a/config/u-boot/qemu_arm64_12mb/target.cfg
+++ b/config/u-boot/qemu_arm64_12mb/target.cfg
@@ -1,2 +1,3 @@
 tree="default"
+xtree="default"
 xarch="aarch64-elf arm-eabi"
diff --git a/config/u-boot/qemu_x86_12mb/target.cfg b/config/u-boot/qemu_x86_12mb/target.cfg
index 2c300b24..216c7bdc 100644
--- a/config/u-boot/qemu_x86_12mb/target.cfg
+++ b/config/u-boot/qemu_x86_12mb/target.cfg
@@ -1,2 +1,3 @@
 tree="default"
+xtree="default"
 xarch="i386-elf"
diff --git a/script/update/trees b/script/update/trees
index 68e4a9f3..fa812f54 100755
--- a/script/update/trees
+++ b/script/update/trees
@@ -12,7 +12,7 @@ set -u -e
 
 eval "$(setvars "" xarch cfgsdir codedir config config_name xlang mode \
     elfdir listfile project target target_dir targets tree _f target1 \
-    bootstrapargs autoconfargs cmakedir makeargs autogenargs)"
+    bootstrapargs autoconfargs cmakedir makeargs autogenargs xtree)"
 
 main()
 {
@@ -159,6 +159,7 @@ check_cross_compiler()
 	for _xarch in $xarch; do
 		cbdir="src/coreboot/${tree}"
 		[ "$project" != "coreboot" ] && cbdir="src/coreboot/default"
+		[ -n "$xtree" ] && cbdir="src/coreboot/$xtree"
 
 		x_ ./update trees -f coreboot ${cbdir#src/coreboot/}