diff --git a/docs/global_substitutions.txt b/docs/global_substitutions.txt
index 24ac830..a70f15e 100644
--- a/docs/global_substitutions.txt
+++ b/docs/global_substitutions.txt
@@ -1,5 +1,7 @@
 .. |AArch32| replace:: :term:`AArch32`
 .. |AArch64| replace:: :term:`AArch64`
+.. |AMU| replace:: :term:`AMU`
+.. |AMUs| replace:: :term:`AMUs <AMU>`
 .. |API| replace:: :term:`API`
 .. |BTI| replace:: :term:`BTI`
 .. |CoT| replace:: :term:`CoT`