diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index bfc50df..630d861 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -721,6 +721,10 @@
   bit, to trap access to the RAS ERR and RAS ERX registers from lower ELs.
   This flag is disabled by default.
 
+- ``OPENSSL_DIR``: This flag is used to provide the installed openssl directory
+  path on the host machine which is used to build certificate generation and
+  firmware encryption tool.
+
 GICv3 driver options
 --------------------