diff --git a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java
index e6c005bd0..112ec98e9 100644
--- a/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java
+++ b/HMCLCore/src/main/java/org/jackhuang/hmcl/download/game/LibraryDownloadTask.java
@@ -18,7 +18,6 @@
 package org.jackhuang.hmcl.download.game;
 
 import org.jackhuang.hmcl.download.AbstractDependencyManager;
-import org.jackhuang.hmcl.download.ArtifactMalformedException;
 import org.jackhuang.hmcl.download.DefaultCacheRepository;
 import org.jackhuang.hmcl.game.Library;
 import org.jackhuang.hmcl.task.DownloadException;
@@ -26,13 +25,12 @@ import org.jackhuang.hmcl.task.FileDownloadTask;
 import org.jackhuang.hmcl.task.FileDownloadTask.IntegrityCheck;
 import org.jackhuang.hmcl.task.Task;
 import org.jackhuang.hmcl.util.DigestUtils;
-import org.jackhuang.hmcl.util.Pack200Utils;
 import org.jackhuang.hmcl.util.io.FileUtils;
 import org.jackhuang.hmcl.util.io.IOUtils;
-import org.jackhuang.hmcl.util.io.NetworkUtils;
-import org.tukaani.xz.XZInputStream;
 
-import java.io.*;
+import java.io.ByteArrayInputStream;
+import java.io.File;
+import java.io.IOException;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
@@ -41,7 +39,6 @@ import java.util.*;
 import java.util.concurrent.CancellationException;
 import java.util.jar.JarEntry;
 import java.util.jar.JarInputStream;
-import java.util.jar.JarOutputStream;
 import java.util.logging.Level;
 
 import static org.jackhuang.hmcl.util.Logging.LOG;
@@ -51,10 +48,8 @@ public class LibraryDownloadTask extends Task<Void> {
     protected final File jar;
     protected final DefaultCacheRepository cacheRepository;
     protected final AbstractDependencyManager dependencyManager;
-    private final File xzFile;
     protected final Library library;
     protected final String url;
-    protected boolean xz;
     private final Library originalLibrary;
     private boolean cached = false;
 
@@ -72,8 +67,6 @@ public class LibraryDownloadTask extends Task<Void> {
 
         url = library.getDownload().getUrl();
         jar = file;
-
-        xzFile = new File(file.getAbsoluteFile().getParentFile(), file.getName() + ".pack.xz");
     }
 
     @Override
@@ -101,8 +94,6 @@ public class LibraryDownloadTask extends Task<Void> {
                 throw new CancellationException();
             else
                 throw new LibraryDownloadException(library, t);
-        } else {
-            if (xz) unpackLibrary(jar, Files.readAllBytes(xzFile.toPath()));
         }
     }
 
@@ -126,36 +117,13 @@ public class LibraryDownloadTask extends Task<Void> {
             }
         }
 
-        if (Pack200Utils.isSupported() && testURLExistence(url)) {
-            List<URL> urls = dependencyManager.getDownloadProvider().injectURLWithCandidates(url + ".pack.xz");
-            task = new FileDownloadTask(urls, xzFile, null);
-            task.setCacheRepository(cacheRepository);
-            task.setCaching(true);
-            xz = true;
-        } else {
-            List<URL> urls = dependencyManager.getDownloadProvider().injectURLWithCandidates(url);
-            task = new FileDownloadTask(urls, jar,
-                    library.getDownload().getSha1() != null ? new IntegrityCheck("SHA-1", library.getDownload().getSha1()) : null);
-            task.setCacheRepository(cacheRepository);
-            task.setCaching(true);
-            task.addIntegrityCheckHandler(FileDownloadTask.ZIP_INTEGRITY_CHECK_HANDLER);
-            xz = false;
-        }
-    }
 
-    private boolean testURLExistence(String rawUrl) {
-        List<URL> urls = dependencyManager.getDownloadProvider().injectURLWithCandidates(rawUrl);
-        for (URL url : urls) {
-            URL xzURL = NetworkUtils.toURL(url.toString() + ".pack.xz");
-            for (int retry = 0; retry < 3; retry++) {
-                try {
-                    return NetworkUtils.urlExists(xzURL);
-                } catch (IOException e) {
-                    LOG.log(Level.WARNING, "Failed to test for url existence: " + url + ".pack.xz", e);
-                }
-            }
-        }
-        return false; // maybe some ugly implementation will give timeout for not existent url.
+        List<URL> urls = dependencyManager.getDownloadProvider().injectURLWithCandidates(url);
+        task = new FileDownloadTask(urls, jar,
+                library.getDownload().getSha1() != null ? new IntegrityCheck("SHA-1", library.getDownload().getSha1()) : null);
+        task.setCacheRepository(cacheRepository);
+        task.setCaching(true);
+        task.addIntegrityCheckHandler(FileDownloadTask.ZIP_INTEGRITY_CHECK_HANDLER);
     }
 
     @Override
@@ -167,7 +135,7 @@ public class LibraryDownloadTask extends Task<Void> {
     public void postExecute() throws Exception {
         if (!cached) {
             try {
-                cacheRepository.cacheLibrary(library, jar.toPath(), xz);
+                cacheRepository.cacheLibrary(library, jar.toPath(), false);
             } catch (IOException e) {
                 LOG.log(Level.WARNING, "Failed to cache downloaded library " + library, e);
             }
@@ -232,44 +200,4 @@ public class LibraryDownloadTask extends Task<Void> {
         }
         return false;
     }
-
-    private static void unpackLibrary(File dest, byte[] src) throws IOException {
-        if (dest.exists())
-            if (!dest.delete())
-                throw new IOException("Unable to delete file " + dest);
-
-        byte[] decompressed;
-        try {
-            decompressed = IOUtils.readFullyAsByteArray(new XZInputStream(new ByteArrayInputStream(src)));
-        } catch (IOException e) {
-            throw new ArtifactMalformedException("Library " + dest + " is malformed");
-        }
-
-        String end = new String(decompressed, decompressed.length - 4, 4);
-        if (!end.equals("SIGN"))
-            throw new IOException("Unpacking failed, signature missing " + end);
-
-        int x = decompressed.length;
-        int len = decompressed[(x - 8)] & 0xFF | (decompressed[(x - 7)] & 0xFF) << 8 | (decompressed[(x - 6)] & 0xFF) << 16 | (decompressed[(x - 5)] & 0xFF) << 24;
-
-        Path temp = Files.createTempFile("minecraft", ".pack");
-
-        byte[] checksums = Arrays.copyOfRange(decompressed, decompressed.length - len - 8, decompressed.length - 8);
-
-        try (OutputStream out = Files.newOutputStream(temp)) {
-            out.write(decompressed, 0, decompressed.length - len - 8);
-        }
-
-        try (FileOutputStream jarBytes = new FileOutputStream(dest); JarOutputStream jos = new JarOutputStream(jarBytes)) {
-            Pack200Utils.unpack(temp.toFile(), jos);
-
-            JarEntry checksumsFile = new JarEntry("checksums.sha1");
-            checksumsFile.setTime(0L);
-            jos.putNextEntry(checksumsFile);
-            jos.write(checksums);
-            jos.closeEntry();
-        }
-
-        Files.delete(temp);
-    }
 }