diff --git a/java/com/googlesource/gerrit/plugins/supermanifest/JiriManifestParser.java b/java/com/googlesource/gerrit/plugins/supermanifest/JiriManifestParser.java
index 538bc2b..80f5e9d 100644
--- a/java/com/googlesource/gerrit/plugins/supermanifest/JiriManifestParser.java
+++ b/java/com/googlesource/gerrit/plugins/supermanifest/JiriManifestParser.java
@@ -65,6 +65,8 @@
   }
 
   static class RepoMap<K, V extends Repository> extends HashMap<K, V> implements AutoCloseable {
+    private static final long serialVersionUID = 1L;
+
     @Override
     public void close() {
       for (Repository repo : this.values()) {