diff --git a/lucene/backward-codecs/src/test/org/apache/lucene/backward_index/TestBackwardsCompatibility.java b/lucene/backward-codecs/src/test/org/apache/lucene/backward_index/TestBackwardsCompatibility.java
index fcb79ad9b7b..a1e209c7e71 100644
--- a/lucene/backward-codecs/src/test/org/apache/lucene/backward_index/TestBackwardsCompatibility.java
+++ b/lucene/backward-codecs/src/test/org/apache/lucene/backward_index/TestBackwardsCompatibility.java
@@ -106,6 +106,7 @@ import org.apache.lucene.store.BaseDirectoryWrapper;
 import org.apache.lucene.store.ByteBuffersDirectory;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.FSDirectory;
+import org.apache.lucene.store.IOContext;
 import org.apache.lucene.store.NIOFSDirectory;
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.BytesRef;
@@ -1642,17 +1643,22 @@ public class TestBackwardsCompatibility extends LuceneTestCase {
     }
   }
 
-  public void testCommandLineArgs() throws Exception {
+  public void testIndexUpgraderCommandLineArgs() throws Exception {
 
     PrintStream savedSystemOut = System.out;
     System.setOut(new PrintStream(new ByteArrayOutputStream(), false, "UTF-8"));
     try {
       for (Map.Entry<String, Directory> entry : oldIndexDirs.entrySet()) {
         String name = entry.getKey();
+        Directory origDir = entry.getValue();
         int indexCreatedVersion =
-            SegmentInfos.readLatestCommit(entry.getValue()).getIndexCreatedVersionMajor();
+            SegmentInfos.readLatestCommit(origDir).getIndexCreatedVersionMajor();
         Path dir = createTempDir(name);
-        TestUtil.unzip(getDataInputStream("index." + name + ".zip"), dir);
+        try (FSDirectory fsDir = FSDirectory.open(dir)) {
+          for (String file : origDir.listAll()) {
+            fsDir.copyFrom(origDir, file, file, IOContext.DEFAULT);
+          }
+        }
 
         String path = dir.toAbsolutePath().toString();