diff --git a/docs/fuchsia_build_instructions.md b/docs/fuchsia_build_instructions.md
index 4dee4bf4..542b7b28 100644
--- a/docs/fuchsia_build_instructions.md
+++ b/docs/fuchsia_build_instructions.md
@@ -160,6 +160,9 @@
 
 `use_goma=true` is fine to use also if you're a Googler.
 
+Architecture options are x64 (default) and arm64. This can be set with
+`target_cpu=arm64`.
+
 ## Build
 
 All targets included in the GN build should build successfully. You can also