diff --git a/stub/src/main/java/com/topjohnwu/magisk/DownloadActivity.java b/stub/src/main/java/com/topjohnwu/magisk/DownloadActivity.java
index 6c033d076..8319b4419 100644
--- a/stub/src/main/java/com/topjohnwu/magisk/DownloadActivity.java
+++ b/stub/src/main/java/com/topjohnwu/magisk/DownloadActivity.java
@@ -140,10 +140,7 @@ public class DownloadActivity extends Activity {
             var is = new CipherInputStream(new ByteArrayInputStream(Bytes.res()), cipher);
             var out = new FileOutputStream(apk);
             try (is; out) {
-                byte[] buf = new byte[4096];
-                for (int read; (read = is.read(buf)) >= 0;) {
-                    out.write(buf, 0, read);
-                }
+                APKInstall.transfer(is, out);
             }
             DynAPK.addAssetPath(getResources().getAssets(), apk.getPath());
         } catch (Exception ignored) {
diff --git a/stub/src/main/java/com/topjohnwu/magisk/DynLoad.java b/stub/src/main/java/com/topjohnwu/magisk/DynLoad.java
index 15762ecc0..a921307e9 100644
--- a/stub/src/main/java/com/topjohnwu/magisk/DynLoad.java
+++ b/stub/src/main/java/com/topjohnwu/magisk/DynLoad.java
@@ -12,33 +12,24 @@ import android.net.Uri;
 import android.os.Build;
 import android.util.Log;
 
+import com.topjohnwu.magisk.utils.APKInstall;
+
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
-import java.io.OutputStream;
 import java.lang.reflect.Field;
 
 import io.michaelrocks.paranoid.Obfuscate;
 
 @Obfuscate
+@SuppressWarnings("ResultOfMethodCallIgnored")
 public class DynLoad {
 
     static Object componentFactory;
     static final DynAPK.Data apkData = createApkData();
 
-    private static void copy(InputStream src, OutputStream dest) throws IOException {
-        try (InputStream s = src) {
-            try (OutputStream o = dest) {
-                byte[] buf = new byte[8192];
-                for (int read; (read = s.read(buf)) >= 0;) {
-                    o.write(buf, 0, read);
-                }
-            }
-        }
-    }
-
     // Dynamically load APK, inject ClassLoader into ContextImpl, then
     // create the actual Application instance from the loaded APK
     static Application inject(Context context) {
@@ -55,7 +46,11 @@ public class DynLoad {
             File external = new File(context.getExternalFilesDir(null), "magisk.apk");
             if (external.exists()) {
                 try {
-                    copy(new FileInputStream(external), new FileOutputStream(apk));
+                    var in = new FileInputStream(external);
+                    var out = new FileOutputStream(apk);
+                    try (in; out) {
+                        APKInstall.transfer(in, out);
+                    }
                 } catch (IOException e) {
                     Log.e(DynLoad.class.getSimpleName(), "", e);
                     apk.delete();
@@ -74,7 +69,10 @@ public class DynLoad {
             try {
                 InputStream src = resolver.openInputStream(uri);
                 if (src != null) {
-                    copy(src, new FileOutputStream(apk));
+                    var out = new FileOutputStream(apk);
+                    try (src; out) {
+                        APKInstall.transfer(src, out);
+                    }
                 }
             } catch (IOException e) {
                 Log.e(DynLoad.class.getSimpleName(), "", e);
@@ -148,6 +146,7 @@ public class DynLoad {
         Field mInfo = context.getClass().getDeclaredField("mPackageInfo");
         mInfo.setAccessible(true);
         Object loadedApk = mInfo.get(context);
+        assert loadedApk != null;
         Field mcl = loadedApk.getClass().getDeclaredField("mClassLoader");
         mcl.setAccessible(true);
         mcl.set(loadedApk, cl);
diff --git a/stub/src/main/java/com/topjohnwu/magisk/net/Request.java b/stub/src/main/java/com/topjohnwu/magisk/net/Request.java
index 4c1c55de7..1187f383e 100644
--- a/stub/src/main/java/com/topjohnwu/magisk/net/Request.java
+++ b/stub/src/main/java/com/topjohnwu/magisk/net/Request.java
@@ -2,6 +2,8 @@ package com.topjohnwu.magisk.net;
 
 import android.os.AsyncTask;
 
+import com.topjohnwu.magisk.utils.APKInstall;
+
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
@@ -24,7 +26,7 @@ import io.michaelrocks.paranoid.Obfuscate;
 
 @Obfuscate
 public class Request implements Closeable {
-    private HttpURLConnection conn;
+    private final HttpURLConnection conn;
     private Executor executor = null;
     private int code = -1;
 
@@ -192,13 +194,9 @@ public class Request implements Closeable {
     }
 
     private File dlFile(File f) throws IOException {
-        try (InputStream in  = getInputStream();
+        try (InputStream in = getInputStream();
              OutputStream out = new BufferedOutputStream(new FileOutputStream(f))) {
-            int len;
-            byte[] buf = new byte[4096];
-            while ((len = in.read(buf)) != -1) {
-                out.write(buf, 0, len);
-            }
+            APKInstall.transfer(in, out);
         }
         return f;
     }
@@ -207,11 +205,8 @@ public class Request implements Closeable {
         int len = conn.getContentLength();
         len = len > 0 ? len : 32;
         ByteArrayOutputStream out = new ByteArrayOutputStream(len);
-        try (InputStream in  = getInputStream()) {
-            byte[] buf = new byte[4096];
-            while ((len = in.read(buf)) != -1) {
-                out.write(buf, 0, len);
-            }
+        try (InputStream in = getInputStream()) {
+            APKInstall.transfer(in, out);
         }
         return out.toByteArray();
     }