diff --git a/core/src/main/java/hudson/diagnosis/NullIdDescriptorMonitor.java b/core/src/main/java/hudson/diagnosis/NullIdDescriptorMonitor.java
index 8892fb1f2ab98aadda857d19f5654ffc385f7875..3182ddc9542fc8b260e0c4322d49d1438c0dc90b 100644
--- a/core/src/main/java/hudson/diagnosis/NullIdDescriptorMonitor.java
+++ b/core/src/main/java/hudson/diagnosis/NullIdDescriptorMonitor.java
@@ -62,6 +62,9 @@ public class NullIdDescriptorMonitor extends AdministrativeMonitor {
 
     private void verify() {
         Jenkins h = Jenkins.getInstance();
+        if (h == null) {
+            return;
+        }
         for (Descriptor d : h.getExtensionList(Descriptor.class)) {
             PluginWrapper p = h.getPluginManager().whichPlugin(d.getClass());
             String id;