diff --git a/src/_includes/partials/faq.md b/src/_includes/partials/faq.md
index 0b7e11a..d6842cd 100644
--- a/src/_includes/partials/faq.md
+++ b/src/_includes/partials/faq.md
@@ -6,6 +6,10 @@
 
 Same as "cuddle".
 
+#### What is the expected file extension?
+
+A file containing KDL should end with `.kdl`.
+
 #### Why yet another document language?
 
 Because nothing out there felt quite right. The closest one I found was