diff --git a/core/src/main/java/hudson/EnvVars.java b/core/src/main/java/hudson/EnvVars.java
index a24976b21916..1d74f26ae9e3 100644
--- a/core/src/main/java/hudson/EnvVars.java
+++ b/core/src/main/java/hudson/EnvVars.java
@@ -74,6 +74,7 @@
  * @author Kohsuke Kawaguchi
  */
 public class EnvVars extends TreeMap<String,String> {
+    private static final long serialVersionUID = 4320331661987259022L;
     private static Logger LOGGER = Logger.getLogger(EnvVars.class.getName());
     /**
      * If this {@link EnvVars} object represents the whole environment variable set,