diff --git a/images/README.md b/images/README.md
index d2efb5db4..63ce46277 100644
--- a/images/README.md
+++ b/images/README.md
@@ -59,3 +59,12 @@ project.
 The continuous integration system can either take fine-grained dependencies on
 individual `push` targets, or ensure all images are up-to-date with a single
 `push-all-images` invocation.
+
+## Multi-Arch images
+
+By default, the image is built for host architecture. Cross-building can be
+achieved by specifying `ARCH` variable to make. For example:
+
+```
+$ make ARCH=aarch64 rebuild-default
+```