diff --git a/docs/user/getting_started.rst b/docs/user/getting_started.rst
index 36eac715..2e374eeb 100644
--- a/docs/user/getting_started.rst
+++ b/docs/user/getting_started.rst
@@ -229,3 +229,7 @@ GLUON_OUTPUTDIR
 
 GLUON_SITEDIR
   Path to the site configuration. Defaults to ``site``.
+
+FOREIGN_BUILD
+  If defined it changes the build-framework into a more generic mode, which will not necessarily 
+  generate a Gluon compatible firmware.