diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveFormat.java b/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveFormat.java
index 85d5d48..152a50a 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveFormat.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveFormat.java
@@ -48,7 +48,7 @@
   /** Unregister all JGit archive formats supported by Gitiles. */
   public static void unregisterAll() {
     for (ArchiveFormat fmt : values()) {
-      ArchiveCommand.unregisterFormat(fmt.getShortName());
+      ArchiveCommand.unregisterFormat(fmt.getRegisteredName());
     }
   }
 
@@ -58,7 +58,11 @@
   private ArchiveFormat(String mimeType, ArchiveCommand.Format<?> format) {
     this.format = format;
     this.mimeType = mimeType;
-    ArchiveCommand.registerFormat(getShortName(), format);
+    ArchiveCommand.registerFormat(getRegisteredName(), format);
+  }
+
+  String getRegisteredName() {
+    return getShortName();
   }
 
   String getShortName() {
diff --git a/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveServlet.java b/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveServlet.java
index d9ef0bf..40777a0 100644
--- a/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveServlet.java
+++ b/gitiles-servlet/src/main/java/com/google/gitiles/ArchiveServlet.java
@@ -69,7 +69,7 @@
 
     try {
       new ArchiveCommand(repo)
-          .setFormat(format.get().name())
+          .setFormat(format.get().getRegisteredName())
           .setTree(treeId)
           .setOutputStream(res.getOutputStream())
           .call();