diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5bcc4d19201..60407e155dc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -56,6 +56,7 @@ You can read more about this in the decision record at `adr/2023-04-libxml-memor
 * Passing a `Nokogiri::XML::Node` as the first parameter to `CDATA.new` is deprecated and will generate a warning. This parameter should be a kind of `Nokogiri::XML::Document`. This will become an error in a future version of Nokogiri.
 * Passing a `Nokogiri::XML::Node` as the first parameter to `Schema.from_document` is deprecated and will generate a warning. This parameter should be a kind of `Nokogiri::XML::Document`. This will become an error in a future version of Nokogiri.
 * Passing a `Nokogiri::XML::Node` as the second parameter to `Text.new` is deprecated and will generate a warning. This parameter should be a kind of `Nokogiri::XML::Document`. This will become an error in a future version of Nokogiri.
+* [CRuby] Calling a custom XPath function without the `nokogiri` namespace is deprecated and will generate a warning. Support for non-namespaced functions will be removed in a future version of Nokogiri. (Note that JRuby has never supported non-namespaced custom XPath functions.)
 
 
 ### Performance