diff --git a/build-userland-in-tree b/build-userland-in-tree
index d6a7c17..0e8b4c2 100755
--- a/build-userland-in-tree
+++ b/build-userland-in-tree
@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 import os
+import platform
 import subprocess
 
 import lkmc.import_path
@@ -14,6 +15,7 @@ class Main(build_userland.Main):
 https://github.com/cirosantilli/linux-kernel-module-cheat#userland-setup-getting-started-natively
 ''',
             defaults={
+                'archs': [platform.processor()],
                 'gcc_which': 'host',
                 'in_tree': True,
                 'targets': ['.'],