diff --git a/java/libphonenumber/test/com/google/i18n/phonenumbers/RegionCode.java b/java/libphonenumber/test/com/google/i18n/phonenumbers/RegionCode.java
index 9ee56c8b7..100cb2930 100644
--- a/java/libphonenumber/test/com/google/i18n/phonenumbers/RegionCode.java
+++ b/java/libphonenumber/test/com/google/i18n/phonenumbers/RegionCode.java
@@ -20,7 +20,7 @@
 
 package com.google.i18n.phonenumbers;
 
-public class RegionCode {
+final class RegionCode {
   // Class containing string constants of region codes for easier testing.
   // Region code for global networks (e.g. +800 numbers).
   static final String UN001 = "001";
diff --git a/tools/java/java-build/src/com/google/i18n/phonenumbers/BuildMetadataProtoFromXml.java b/tools/java/java-build/src/com/google/i18n/phonenumbers/BuildMetadataProtoFromXml.java
index 7532ade87..748d26351 100644
--- a/tools/java/java-build/src/com/google/i18n/phonenumbers/BuildMetadataProtoFromXml.java
+++ b/tools/java/java-build/src/com/google/i18n/phonenumbers/BuildMetadataProtoFromXml.java
@@ -26,8 +26,7 @@ import java.io.FileWriter;
 import java.io.IOException;
 import java.io.ObjectOutputStream;
 import java.io.Writer;
-import java.util.ArrayList;
-import java.util.Arrays;
+import java.util.Collection;
 import java.util.Formatter;
 import java.util.List;
 import java.util.Map;
@@ -103,6 +102,9 @@ public class BuildMetadataProtoFromXml extends Command {
       " * Please don't modify it directly.\n" +
       " */\n\n";
 
+  private static final String REGION_CODE_CONSTS_COMMENT =
+      "  // Class containing string constants of region codes for easier testing.\n";
+
   @Override
   public String getCommandName() {
     return CLASS_NAME;
@@ -208,12 +210,12 @@ public class BuildMetadataProtoFromXml extends Command {
       
       if (buildRegioncode) {
         SortedSet<String> regionCodeSet = new TreeSet<String>();
-        regionCodeSet.addAll(getDefaultRegionCodeList());
+        // Official code for the unknown region.
+        regionCodeSet.add("ZZ");
         regionCodeSet.addAll(BuildMetadataFromXml.buildRegionCodeList(metadataCollection));
-        List<String> regionCodeList = new ArrayList<String>(regionCodeSet);
-        System.out.println("Found " + regionCodeList.size() + " region codes");
+        System.out.println("Found " + regionCodeSet.size() + " region codes");
         
-        writeRegionCodeConstantsToJavaFile(regionCodeList, outputDir, copyright);
+        writeRegionCodeConstantsToJavaFile(regionCodeSet, outputDir, copyright);
       }
     } catch (Exception e) {
       e.printStackTrace();
@@ -359,11 +361,8 @@ public class BuildMetadataProtoFromXml extends Command {
     writer.addToBody("  }\n");
   }
 
-  private static final String REGION_CODE_CONSTS_COMMENT =
-      "  // Class containing string constants of region codes for easier testing.\n";
-
-  private static void writeRegionCodeConstantsToJavaFile(List<String> regionCodeList, String outputDir, String copyright) throws IOException {
-    ClassWriter writer = new ClassWriter(outputDir, "RegionCode", copyright);
+  private static void writeRegionCodeConstantsToJavaFile(Collection<String> regionCodeList, String outputDir, String copyright) throws IOException {
+    ClassWriter writer = new ClassWriter(outputDir, "RegionCode", copyright, "final");
     writer.addToBody(REGION_CODE_CONSTS_COMMENT);
     
     for (String regionCode : regionCodeList) {
@@ -380,23 +379,20 @@ public class BuildMetadataProtoFromXml extends Command {
     writer.writeToFile();
   }
 
-  private static List<String> getDefaultRegionCodeList() {
-    // hard-coded list of region codes to include in the RegionCode class
-    return Arrays.asList("ZZ");
-  }
-
   private static final class ClassWriter {
     private final String name;
     private final String copyright;
+    private final String modifiers;
 
     private final SortedSet<String> imports;
     private final StringBuffer body;
     private final Formatter formatter;
     private final Writer writer;
 
-    ClassWriter(String outputDir, String name, String copyright) throws IOException {
+    ClassWriter(String outputDir, String name, String copyright, String modifiers) throws IOException {
       this.name = name;
       this.copyright = copyright;
+      this.modifiers = modifiers;
 
       imports = new TreeSet<String>();
       body = new StringBuffer();
@@ -404,6 +400,10 @@ public class BuildMetadataProtoFromXml extends Command {
       writer = new BufferedWriter(new FileWriter(new File(outputDir, name + ".java")));
     }
 
+    ClassWriter(String outputDir, String name, String copyright) throws IOException {
+      this(outputDir, name, copyright, "public");
+    }
+
     void addToImports(String name) {
       imports.add(name);
     }
@@ -428,7 +428,7 @@ public class BuildMetadataProtoFromXml extends Command {
         writer.write("\n");
       }
 
-      writer.write("public class " + name + " {\n");
+      writer.write((modifiers.isEmpty() ? "" : modifiers + " ") + "class " + name + " {\n");
       writer.write(body.toString());
       writer.write("}\n");