diff --git a/app/src/main/java/us/shandian/giga/get/DownloadMission.java b/app/src/main/java/us/shandian/giga/get/DownloadMission.java
index c48e5ffbc..f02eaae28 100644
--- a/app/src/main/java/us/shandian/giga/get/DownloadMission.java
+++ b/app/src/main/java/us/shandian/giga/get/DownloadMission.java
@@ -5,6 +5,7 @@ import android.os.Looper;
 import android.util.Log;
 
 import java.io.File;
+import java.io.ObjectInputStream;
 import java.io.Serializable;
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
@@ -312,6 +313,13 @@ public class DownloadMission implements Serializable {
         }
     }
 
+    private void readObject(ObjectInputStream inputStream)
+    throws java.io.IOException, ClassNotFoundException
+    {
+        inputStream.defaultReadObject();
+        mListeners = new ArrayList<>();
+    }
+
     private void deleteThisFromFile() {
         new File(getMetaFilename()).delete();
     }
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 2d44e8c15..de9a16a1b 100644
--- a/app/src/main/java/us/shandian/giga/util/Utility.java
+++ b/app/src/main/java/us/shandian/giga/util/Utility.java
@@ -12,6 +12,7 @@ import android.widget.Toast;
 import org.schabi.newpipe.R;
 
 import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
@@ -59,17 +60,17 @@ public class Utility {
         ObjectOutputStream objectOutputStream = null;
 
         try {
-            objectOutputStream = new ObjectOutputStream(new FileOutputStream(fileName));
+            objectOutputStream = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(fileName)));
             objectOutputStream.writeObject(serializable);
         } catch (Exception e) {
             //nothing to do
-        }
-
-        if(objectOutputStream != null) {
-            try {
-                objectOutputStream.close();
-            } catch (Exception e) {
-                //nothing to do
+        } finally {
+            if(objectOutputStream != null) {
+                try {
+                    objectOutputStream.close();
+                } catch (Exception e) {
+                    //nothing to do
+                }
             }
         }
     }