diff --git a/src/eu/siacs/conversations/entities/Account.java b/src/eu/siacs/conversations/entities/Account.java
index b19889bf..5883788f 100644
--- a/src/eu/siacs/conversations/entities/Account.java
+++ b/src/eu/siacs/conversations/entities/Account.java
@@ -1,7 +1,6 @@
 package eu.siacs.conversations.entities;
 
 import java.security.interfaces.DSAPublicKey;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -68,7 +67,7 @@ public class Account  extends AbstractEntity{
 	
 	private Roster roster = null;
 
-	private List<Bookmark> bookmarks = new ArrayList<Bookmark>();
+	private List<Bookmark> bookmarks = new CopyOnWriteArrayList<Bookmark>();
 	
 	public List<Conversation> pendingConferenceJoins = new CopyOnWriteArrayList<Conversation>();
 	public List<Conversation> pendingConferenceLeaves = new CopyOnWriteArrayList<Conversation>();
diff --git a/src/eu/siacs/conversations/entities/Conversation.java b/src/eu/siacs/conversations/entities/Conversation.java
index 76fe84cf..29eb22b9 100644
--- a/src/eu/siacs/conversations/entities/Conversation.java
+++ b/src/eu/siacs/conversations/entities/Conversation.java
@@ -1,8 +1,8 @@
 package eu.siacs.conversations.entities;
 
 import java.security.interfaces.DSAPublicKey;
-import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import net.java.otr4j.OtrException;
 import net.java.otr4j.crypto.OtrCryptoEngineImpl;
@@ -43,7 +43,7 @@ public class Conversation extends AbstractEntity {
 
 	private String nextPresence;
 
-	private transient List<Message> messages = null;
+	private transient CopyOnWriteArrayList<Message> messages = null;
 	private transient Account account = null;
 
 	private transient SessionImpl otrSession;
@@ -85,8 +85,9 @@ public class Conversation extends AbstractEntity {
 	}
 
 	public List<Message> getMessages() {
-		if (messages == null)
-			this.messages = new ArrayList<Message>(); // prevent null pointer
+		if (messages == null) {
+			this.messages = new CopyOnWriteArrayList<Message>(); // prevent null pointer
+		}
 
 		// populate with Conversation (this)
 
@@ -133,7 +134,7 @@ public class Conversation extends AbstractEntity {
 		}
 	}
 
-	public void setMessages(List<Message> msgs) {
+	public void setMessages(CopyOnWriteArrayList<Message> msgs) {
 		this.messages = msgs;
 	}
 
diff --git a/src/eu/siacs/conversations/entities/MucOptions.java b/src/eu/siacs/conversations/entities/MucOptions.java
index 0bb9b295..3bce5111 100644
--- a/src/eu/siacs/conversations/entities/MucOptions.java
+++ b/src/eu/siacs/conversations/entities/MucOptions.java
@@ -2,6 +2,7 @@ package eu.siacs.conversations.entities;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import eu.siacs.conversations.crypto.PgpEngine;
 import eu.siacs.conversations.xml.Element;
@@ -81,7 +82,7 @@ public class MucOptions {
 		}
 	}
 	private Account account;
-	private ArrayList<User> users = new ArrayList<User>();
+	private List<User> users = new CopyOnWriteArrayList<User>();
 	private Conversation conversation;
 	private boolean isOnline = false;
 	private int error = ERROR_ROOM_NOT_FOUND;
diff --git a/src/eu/siacs/conversations/persistance/DatabaseBackend.java b/src/eu/siacs/conversations/persistance/DatabaseBackend.java
index 7643076a..d840721b 100644
--- a/src/eu/siacs/conversations/persistance/DatabaseBackend.java
+++ b/src/eu/siacs/conversations/persistance/DatabaseBackend.java
@@ -129,12 +129,12 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 		return list;
 	}
 	
-	public List<Message> getMessages(Conversation conversations, int limit) {
+	public CopyOnWriteArrayList<Message> getMessages(Conversation conversations, int limit) {
 		return getMessages(conversations, limit,-1);
 	}
 
-	public List<Message> getMessages(Conversation conversation, int limit, long timestamp) {
-		List<Message> list = new CopyOnWriteArrayList<Message>();
+	public CopyOnWriteArrayList<Message> getMessages(Conversation conversation, int limit, long timestamp) {
+		CopyOnWriteArrayList<Message> list = new CopyOnWriteArrayList<Message>();
 		SQLiteDatabase db = this.getReadableDatabase();
 		Cursor cursor;
 		if (timestamp==-1) {
diff --git a/src/eu/siacs/conversations/services/XmppConnectionService.java b/src/eu/siacs/conversations/services/XmppConnectionService.java
index c9813d82..3f9b3bfb 100644
--- a/src/eu/siacs/conversations/services/XmppConnectionService.java
+++ b/src/eu/siacs/conversations/services/XmppConnectionService.java
@@ -668,7 +668,7 @@ public class XmppConnectionService extends Service {
 			@Override
 			public void onIqPacketReceived(Account account, IqPacket packet) {
 				Element query = packet.query();
-				List<Bookmark> bookmarks = new ArrayList<Bookmark>();
+				List<Bookmark> bookmarks = new CopyOnWriteArrayList<Bookmark>();
 				Element storage = query.findChild("storage", "storage:bookmarks");
 				if (storage!=null) {
 					for(Element item : storage.getChildren()) {
diff --git a/src/eu/siacs/conversations/xmpp/XmppConnection.java b/src/eu/siacs/conversations/xmpp/XmppConnection.java
index f335d9d4..6d01825e 100644
--- a/src/eu/siacs/conversations/xmpp/XmppConnection.java
+++ b/src/eu/siacs/conversations/xmpp/XmppConnection.java
@@ -7,14 +7,8 @@ import java.math.BigInteger;
 import java.net.Socket;
 import java.net.UnknownHostException;
 import java.security.KeyManagementException;
-import java.security.KeyStore;
-import java.security.KeyStoreException;
-import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
-import java.security.cert.CertPathValidatorException;
-import java.security.cert.CertificateException;
-import java.security.cert.X509Certificate;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Hashtable;
@@ -25,16 +19,13 @@ import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLContext;
 import javax.net.ssl.SSLSocket;
 import javax.net.ssl.SSLSocketFactory;
-import javax.net.ssl.TrustManager;
-import javax.net.ssl.TrustManagerFactory;
+
 import javax.net.ssl.X509TrustManager;
 
-import org.bouncycastle.pqc.math.linearalgebra.GoppaCode.MaMaPe;
 import org.xmlpull.v1.XmlPullParserException;
 
 import de.duenndns.ssl.MemorizingTrustManager;
 
-import android.content.Context;
 import android.os.Bundle;
 import android.os.PowerManager;
 import android.os.PowerManager.WakeLock;