diff --git a/docs/deployment/builders/cloud-native-buildpacks.md b/docs/deployment/builders/cloud-native-buildpacks.md
index 17d2734cd..fbaf1db37 100644
--- a/docs/deployment/builders/cloud-native-buildpacks.md
+++ b/docs/deployment/builders/cloud-native-buildpacks.md
@@ -69,7 +69,7 @@ dokku buildpacks:set-property node-js-app stack
 
 A change in the stack builder value will execute the `post-stack-set` trigger.
 
-Finally, stack builders can be set or unset globally as a fallback. This will take precedence over a globally set `DOKKU_CNB_STACK` environment variable (`heroku/buildpacks` by default).
+Finally, stack builders can be set or unset globally as a fallback. This will take precedence over a globally set `DOKKU_CNB_BUILDER` environment variable (`heroku/buildpacks` by default).
 
 ```shell
 # set globally
diff --git a/plugins/builder-pack/builder-build b/plugins/builder-pack/builder-build
index d1dcd96f8..93dcd6b70 100755
--- a/plugins/builder-pack/builder-build
+++ b/plugins/builder-pack/builder-build
@@ -14,11 +14,11 @@ trigger-builder-pack-builder-build() {
   fi
 
   local stack="$(plugn trigger buildpack-stack-name "$APP")"
-  if [[ -z "$stack" ]]; then
-    DOKKU_CNB_STACK="$stack"
+  if [[ -n "$stack" ]]; then
+    DOKKU_CNB_BUILDER="$stack"
   fi
 
-  dokku_log_info1 "Building $APP from cnb stack $DOKKU_CNB_STACK (experimental)..."
+  dokku_log_info1 "Building $APP from cnb stack $DOKKU_CNB_BUILDER (experimental)..."
 
   if ! command -v "pack" &>/dev/null; then
     dokku_log_fail "Missing pack, install it"