diff --git a/src/lib/custom-style.html b/src/lib/custom-style.html
index 054a46e513..d789ec531d 100644
--- a/src/lib/custom-style.html
+++ b/src/lib/custom-style.html
@@ -13,7 +13,7 @@
 
 <!-- 
 
-The `x-style` extension of the native `<style>` element allows defining styles
+The `custom-style` extension of the native `<style>` element allows defining styles
 in the main document that can take advantage of several special features of
 Polymer's styling system: