diff --git a/app/src/main/java/us/shandian/giga/get/DownloadInitializer.java b/app/src/main/java/us/shandian/giga/get/DownloadInitializer.java
index 7c0fa9012..1d5a93588 100644
--- a/app/src/main/java/us/shandian/giga/get/DownloadInitializer.java
+++ b/app/src/main/java/us/shandian/giga/get/DownloadInitializer.java
@@ -54,12 +54,12 @@ public class DownloadInitializer extends Thread {
                     long lowestSize = Long.MAX_VALUE;
 
                     for (int i = 0; i < mMission.urls.length && mMission.running; i++) {
-                        mConn = mMission.openConnection(mMission.urls[i], true, -1, -1);
+                        mConn = mMission.openConnection(mMission.urls[i], true, 0, 0);
                         mMission.establishConnection(mId, mConn);
                         dispose();
 
                         if (Thread.interrupted()) return;
-                        long length = Utility.getContentLength(mConn);
+                        long length = Utility.getTotalContentLength(mConn);
 
                         if (i == 0) {
                             httpCode = mConn.getResponseCode();
@@ -84,14 +84,14 @@ public class DownloadInitializer extends Thread {
                     }
                 } else {
                     // ask for the current resource length
-                    mConn = mMission.openConnection(true, -1, -1);
+                    mConn = mMission.openConnection(true, 0, 0);
                     mMission.establishConnection(mId, mConn);
                     dispose();
 
                     if (!mMission.running || Thread.interrupted()) return;
 
                     httpCode = mConn.getResponseCode();
-                    mMission.length = Utility.getContentLength(mConn);
+                    mMission.length = Utility.getTotalContentLength(mConn);
                 }
 
                 if (mMission.length == 0 || httpCode == 204) {
diff --git a/app/src/main/java/us/shandian/giga/util/Utility.java b/app/src/main/java/us/shandian/giga/util/Utility.java
index ecce6639e..3cfa22bd9 100644
--- a/app/src/main/java/us/shandian/giga/util/Utility.java
+++ b/app/src/main/java/us/shandian/giga/util/Utility.java
@@ -1,11 +1,8 @@
 package us.shandian.giga.util;
 
-import android.content.ClipData;
-import android.content.ClipboardManager;
 import android.content.Context;
 import android.os.Build;
 import android.util.Log;
-import android.widget.Toast;
 
 import androidx.annotation.ColorInt;
 import androidx.annotation.DrawableRes;
@@ -29,8 +26,10 @@ import java.io.ObjectOutputStream;
 import java.io.Serializable;
 import java.net.HttpURLConnection;
 import java.util.Locale;
+import java.util.Random;
 
 import okio.ByteString;
+import us.shandian.giga.get.DownloadMission;
 
 public class Utility {
 
@@ -232,6 +231,28 @@ public class Utility {
         return -1;
     }
 
+    /**
+     * Get the content length of the entire file even if the HTTP response is partial
+     * (response code 206).
+     * @param connection http connection
+     * @return content length
+     */
+    public static long getTotalContentLength(final HttpURLConnection connection) {
+        try {
+            if (connection.getResponseCode() == 206) {
+                final String rangeStr = connection.getHeaderField("Content-Range");
+                final String bytesStr = rangeStr.split("/", 2)[1];
+                return Long.parseLong(bytesStr);
+            } else {
+                return getContentLength(connection);
+            }
+        } catch (Exception err) {
+            // nothing to do
+        }
+
+        return -1;
+    }
+
     private static String pad(int number) {
         return number < 10 ? ("0" + number) : String.valueOf(number);
     }