diff --git a/script/trees b/script/trees
index d3ac03f..2cee435 100755
--- a/script/trees
+++ b/script/trees
@@ -204,6 +204,7 @@ check_project_hashes()
 
 check_cross_compiler()
 {
+	xgccargs="UPDATED_SUBMODULES=1 CPUS=$XBMK_THREADS"
 	for _xarch in $xarch; do
 		cbdir="src/coreboot/$tree"
 		[ "$project" != "coreboot" ] && cbdir="src/coreboot/default"
@@ -216,9 +217,9 @@ check_cross_compiler()
 		[ -n "$xlang" ] && export BUILD_LANGUAGES="$xlang"
 
 		# sometimes buildgcc fails for like no reason. try twice.
-		make -C "$cbdir" crossgcc-${_xarch%-*} $makeargs || \
-		    make -C "$cbdir" crossgcc-${_xarch%-*} $makeargs || \
-		    $err "!mkxgcc $project/$xtree '${_xarch%-*}' '$makeargs'"
+		make -C "$cbdir" crossgcc-${_xarch%-*} $xgccargs || \
+		    make -C "$cbdir" crossgcc-${_xarch%-*} $xgccargs || \
+		    $err "!mkxgcc $project/$xtree '${_xarch%-*}' '$xgccargs'"
 	done; return 0
 }