diff --git a/setup.cfg b/setup.cfg
index 43a86b85..15786025 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -58,6 +58,7 @@ install_requires =
     metomi-rose==2.1.*
     cylc-flow==8.2.*
     metomi-isodatetime
+    ansimarkup
     jinja2
 
 [options.packages.find]