diff --git a/src/main/java/org/jenkins/plugins/lockableresources/LockableResource.java b/src/main/java/org/jenkins/plugins/lockableresources/LockableResource.java
index acb0aefe4..af06f8fec 100644
--- a/src/main/java/org/jenkins/plugins/lockableresources/LockableResource.java
+++ b/src/main/java/org/jenkins/plugins/lockableresources/LockableResource.java
@@ -136,6 +136,9 @@ protected Object readResolve() {
     if (queuedContexts == null) { // this field was added after the initial version if this class
       queuedContexts = new ArrayList<>();
     }
+    if (properties == null) {
+      properties = new ArrayList<>();
+    }
     this.repairLabels();
     return this;
   }