diff --git a/dual-master/README.md b/dual-master/README.md
index 359099d..01abceb 100644
--- a/dual-master/README.md
+++ b/dual-master/README.md
@@ -132,6 +132,9 @@
 they will be retained during the stack deletion, so that they can still be used
 by the green stack.
 
+This includes EFS as well as VPC resources (if they were created as part of the
+blue stack).
+
 ### Logging
 
 * All the logs are forwarded to AWS CloudWatch in the LogGroup with the cluster
diff --git a/dual-master/cf-cluster.yml b/dual-master/cf-cluster.yml
index 0c37ad4..841e7e0 100644
--- a/dual-master/cf-cluster.yml
+++ b/dual-master/cf-cluster.yml
@@ -312,6 +312,7 @@
 
   ECSTaskNetworkStack:
     Type: AWS::CloudFormation::Stack
+    DeletionPolicy: Retain
     Properties:
       TemplateURL: !Join [ '', ['https://', !Ref TemplateBucketName, '.s3.amazonaws.com/cf-gerrit-network-stack.yml'] ]
       TimeoutInMinutes: '25'