diff --git a/cylc/sphinx_ext/__init__.py b/cylc/sphinx_ext/__init__.py
index 094ac74..9ffb74e 100644
--- a/cylc/sphinx_ext/__init__.py
+++ b/cylc/sphinx_ext/__init__.py
@@ -23,7 +23,7 @@
 from shutil import copyfile
 
 
-__version__ = '1.3.4'
+__version__ = '1.4.0'
 
 
 # map sub directory name to the name of the sphinx registration function