diff --git a/plone-5.2.x-performance.cfg b/plone-5.2.x-performance.cfg
index 8285f1ddf0..02d3217951 100644
--- a/plone-5.2.x-performance.cfg
+++ b/plone-5.2.x-performance.cfg
@@ -1,7 +1,7 @@
 [buildout]
 extends = plone-5.2.x.cfg
 parts += instance plonesite
-auto-checkout = Products.ZCatalog
+auto-checkout += Products.ZCatalog
 
 [instance]
 recipe = plone.recipe.zope2instance
diff --git a/plone-6.0.x.cfg b/plone-6.0.x.cfg
index 1360f78d25..dff3b5fc5f 100644
--- a/plone-6.0.x.cfg
+++ b/plone-6.0.x.cfg
@@ -5,7 +5,7 @@ extends =
     base.cfg
 find-links = https://dist.plone.org/release/6.0.0a3/
 versions=versions
-auto-checkout =
+auto-checkout +=
     Products.CMFPlone
 
 [sources]
diff --git a/site.cfg b/site.cfg
index eb81698e9d..0114638d9c 100644
--- a/site.cfg
+++ b/site.cfg
@@ -2,7 +2,7 @@
 extensions = mr.developer
 extends = buildout.cfg
 eggs += plone.restapi
-auto-checkout = plone.restapi
+auto-checkout += plone.restapi
 parts = instance plonesite