diff --git a/site/conf.py b/site/conf.py
index a5f449a38..9f6b70f38 100644
--- a/site/conf.py
+++ b/site/conf.py
@@ -73,7 +73,7 @@
 # -- Options for MyST-NB configuration -----------------------------------
 
 # Bump up per cell execution timeout to 300 seconds (from default 30 seconds)
-execution_timeout = 300
+nb_execution_timeout = 300
 
 # if `True` then a transition line(----) will be placed before any footnotes
 myst_footnote_transition = False