diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 43b13d6..4b54829 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -677,6 +677,10 @@
    invert this behavior. Lower addresses will be printed at the top and higher
    addresses at the bottom.
 
+-  ``INIT_UNUSED_NS_EL2``: This build flag guards code that disables EL2
+   safely in scenario where NS-EL2 is present but unused. This flag is set to 0
+   by default. Platforms without NS-EL2 in use must enable this flag.
+
 -  ``KEY_ALG``: This build flag enables the user to select the algorithm to be
    used for generating the PKCS keys and subsequent signing of the certificate.
    It accepts 5 values: ``rsa``, ``rsa_1_5``, ``ecdsa``, ``ecdsa-brainpool-regular``