diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3d957b0ef..9433b4020 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Deprecate CNB support, CNB users should use [heroku/buildpacks-ruby](https://github.com/heroku/buildpacks-ruby) instead ()
 
 ## [v268] - 2024-04-17
 
diff --git a/bin/build b/bin/build
index 016645c90..d19b67ad2 100755
--- a/bin/build
+++ b/bin/build
@@ -8,10 +8,18 @@ APP_DIR=$(pwd)
 BIN_DIR=$(cd $(dirname $0); pwd)
 BUILDPACK_DIR=$(dirname $BIN_DIR)
 
-# legacy buildpack uses $STACK 
+# legacy buildpack uses $STACK
 export STACK=$CNB_STACK_ID
 
 source "$BIN_DIR/support/bash_functions.sh"
 heroku_buildpack_ruby_install_ruby "$BIN_DIR" "$BUILDPACK_DIR"
 
+cat<<EOF 1>&2
+    CNB no longer maintained
+
+    The heroku/heroku-ruby-buildpack previously implemented the Cloud Native Buildpack \(CNB\) spec beta support, however this functionality is no longer supported or maintained.
+
+    The Heroku Ruby CNB is now at https://github.com/heroku/buildpacks-ruby. See https://github.com/heroku/buildpacks for more information on using the Heroku CNB builder. To avoid interruptions switch to the new CNB as soon as possible.
+EOF
+
 $heroku_buildpack_ruby_dir/bin/ruby $BIN_DIR/support/ruby_build $APP_DIR $LAYERS_DIR $PLATFORM_DIR $PLAN