diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index bb12d7d..c1a3cb7 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -603,6 +603,9 @@
 -  ``ERRATA_N2_2002655``: This applies errata 2002655 workaround to Neoverse-N2
    CPU. This needs to be enabled for revision r0p0 of the CPU and is fixed in r0p1.
 
+-  ``ERRATA_N2_2009478``: This applies errata 2009478 workaround to Neoverse-N2
+   CPU. This needs to be enabled for revision r0p0 of the CPU and is fixed in r0p1.
+
 -  ``ERRATA_N2_2067956``: This applies errata 2067956 workaround to Neoverse-N2
    CPU. This needs to be enabled for revision r0p0 of the CPU and is fixed in r0p1.