diff --git a/doc/sphinx/src/building.rst b/doc/sphinx/src/building.rst
index 6dc37ce57c..602b620a35 100644
--- a/doc/sphinx/src/building.rst
+++ b/doc/sphinx/src/building.rst
@@ -118,6 +118,8 @@ The main CMake options to configure building are in the following table:
  ``SINGULARITY_USE_SINGLE_LOGS``         OFF      Use single precision logarithms (may degrade accuracy).
  ``SINGULARITY_NQT_ORDER_1``             OFF      For fast logs, use the less accurate but faster 1st-order version.
  ``SINGULARITY_NQT_PORTABLE``            OFF      For fast logs, use the slower but endianness-independent implementation.
+ ``SINGULARITY_BUILD_FORTRAN_BACKEND``   OFF      For testing, you may build the C++ code to which the fortran bindings bind
+ ``SINGULARITY_STRICT_WARNINGS``         OFF      For testing. Adds -Wall and -Werror to builds.
 ====================================== ======= ===========================================
 
 More options are available to modify only if certain other options or