diff --git a/core/src/main/java/hudson/tasks/BuildTrigger.java b/core/src/main/java/hudson/tasks/BuildTrigger.java
index 6852edb85033678846f6de2f9ece2d7e9ff4e101..de885c7c0bdb49213b69cab91df6f69616800826 100644
--- a/core/src/main/java/hudson/tasks/BuildTrigger.java
+++ b/core/src/main/java/hudson/tasks/BuildTrigger.java
@@ -177,6 +177,15 @@ public class BuildTrigger extends Publisher implements DependecyDeclarer, Matrix
         return changed;
     }
 
+    /**
+     * Correct broken data gracefully (#1537)
+     */
+    private Object readResolve() {
+        if(childProjects==null)
+            return childProjects="";
+        return this;
+    }
+
     public Descriptor<Publisher> getDescriptor() {
         return DESCRIPTOR;
     }