diff --git a/src/main/java/eu/siacs/conversations/services/XmppConnectionService.java b/src/main/java/eu/siacs/conversations/services/XmppConnectionService.java
index 90a460b77..8c11974ef 100644
--- a/src/main/java/eu/siacs/conversations/services/XmppConnectionService.java
+++ b/src/main/java/eu/siacs/conversations/services/XmppConnectionService.java
@@ -57,6 +57,7 @@ import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
 import java.util.Set;
+import java.util.WeakHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -259,14 +260,16 @@ public class XmppConnectionService extends Service {
 	private int unreadCount = -1;
 
 	//Ui callback listeners
-	private final List<OnConversationUpdate> mOnConversationUpdates = new ArrayList<>();
-	private final List<OnShowErrorToast> mOnShowErrorToasts = new ArrayList<>();
-	private final List<OnAccountUpdate> mOnAccountUpdates = new ArrayList<>();
-	private final List<OnCaptchaRequested> mOnCaptchaRequested = new ArrayList<>();
-	private final List<OnRosterUpdate> mOnRosterUpdates = new ArrayList<>();
-	private final List<OnUpdateBlocklist> mOnUpdateBlocklist = new ArrayList<>();
-	private final List<OnMucRosterUpdate> mOnMucRosterUpdate = new ArrayList<>();
-	private final List<OnKeyStatusUpdated> mOnKeyStatusUpdated = new ArrayList<>();
+	private final Set<OnConversationUpdate> mOnConversationUpdates = Collections.newSetFromMap(new WeakHashMap<OnConversationUpdate, Boolean>());
+	private final Set<OnShowErrorToast> mOnShowErrorToasts = Collections.newSetFromMap(new WeakHashMap<OnShowErrorToast, Boolean>());
+	private final Set<OnAccountUpdate> mOnAccountUpdates = Collections.newSetFromMap(new WeakHashMap<OnAccountUpdate, Boolean>());
+	private final Set<OnCaptchaRequested> mOnCaptchaRequested = Collections.newSetFromMap(new WeakHashMap<OnCaptchaRequested, Boolean>());
+	private final Set<OnRosterUpdate> mOnRosterUpdates = Collections.newSetFromMap(new WeakHashMap<OnRosterUpdate, Boolean>());
+	private final Set<OnUpdateBlocklist> mOnUpdateBlocklist = Collections.newSetFromMap(new WeakHashMap<OnUpdateBlocklist, Boolean>());
+	private final Set<OnMucRosterUpdate> mOnMucRosterUpdate = Collections.newSetFromMap(new WeakHashMap<OnMucRosterUpdate, Boolean>());
+	private final Set<OnKeyStatusUpdated> mOnKeyStatusUpdated = Collections.newSetFromMap(new WeakHashMap<OnKeyStatusUpdated, Boolean>());
+
+	private final Object LISTENER_LOCK = new Object();
 
 
 	private final OnBindListener mOnBindListener = new OnBindListener() {
@@ -1889,17 +1892,19 @@ public class XmppConnectionService extends Service {
 	}
 
 	public void setOnConversationListChangedListener(OnConversationUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnConversationUpdates.add(listener);
+			if (!this.mOnConversationUpdates.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as ConversationListChangedListener");
+			}
 			this.mNotificationService.setIsInForeground(this.mOnConversationUpdates.size() > 0);
 		}
 	}
 
 	public void removeOnConversationListChangedListener(OnConversationUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnConversationUpdates.remove(listener);
 			this.mNotificationService.setIsInForeground(this.mOnConversationUpdates.size() > 0);
 			if (checkListeners()) {
@@ -1908,17 +1913,19 @@ public class XmppConnectionService extends Service {
 		}
 	}
 
-	public void setOnShowErrorToastListener(OnShowErrorToast onShowErrorToast) {
-		synchronized (this) {
+	public void setOnShowErrorToastListener(OnShowErrorToast listener) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnShowErrorToasts.add(onShowErrorToast);
+			if (!this.mOnShowErrorToasts.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as OnShowErrorToastListener");
+			}
 		}
 	}
 
 	public void removeOnShowErrorToastListener(OnShowErrorToast onShowErrorToast) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnShowErrorToasts.remove(onShowErrorToast);
 			if (checkListeners()) {
 				switchToBackground();
@@ -1927,16 +1934,18 @@ public class XmppConnectionService extends Service {
 	}
 
 	public void setOnAccountListChangedListener(OnAccountUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnAccountUpdates.add(listener);
+			if (!this.mOnAccountUpdates.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as OnAccountListChangedtListener");
+			}
 		}
 	}
 
 	public void removeOnAccountListChangedListener(OnAccountUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnAccountUpdates.remove(listener);
 			if (checkListeners()) {
 				switchToBackground();
@@ -1945,16 +1954,18 @@ public class XmppConnectionService extends Service {
 	}
 
 	public void setOnCaptchaRequestedListener(OnCaptchaRequested listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnCaptchaRequested.add(listener);
+			if (!this.mOnCaptchaRequested.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as OnCaptchaRequestListener");
+			}
 		}
 	}
 
 	public void removeOnCaptchaRequestedListener(OnCaptchaRequested listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnCaptchaRequested.remove(listener);
 			if (checkListeners()) {
 				switchToBackground();
@@ -1963,16 +1974,18 @@ public class XmppConnectionService extends Service {
 	}
 
 	public void setOnRosterUpdateListener(final OnRosterUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnRosterUpdates.add(listener);
+			if (!this.mOnRosterUpdates.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as OnRosterUpdateListener");
+			}
 		}
 	}
 
 	public void removeOnRosterUpdateListener(final OnRosterUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnRosterUpdates.remove(listener);
 			if (checkListeners()) {
 				switchToBackground();
@@ -1981,16 +1994,18 @@ public class XmppConnectionService extends Service {
 	}
 
 	public void setOnUpdateBlocklistListener(final OnUpdateBlocklist listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnUpdateBlocklist.add(listener);
+			if (!this.mOnUpdateBlocklist.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as OnUpdateBlocklistListener");
+			}
 		}
 	}
 
 	public void removeOnUpdateBlocklistListener(final OnUpdateBlocklist listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnUpdateBlocklist.remove(listener);
 			if (checkListeners()) {
 				switchToBackground();
@@ -1999,16 +2014,18 @@ public class XmppConnectionService extends Service {
 	}
 
 	public void setOnKeyStatusUpdatedListener(final OnKeyStatusUpdated listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnKeyStatusUpdated.add(listener);
+			if (!this.mOnKeyStatusUpdated.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as OnKeyStatusUpdateListener");
+			}
 		}
 	}
 
 	public void removeOnNewKeysAvailableListener(final OnKeyStatusUpdated listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnKeyStatusUpdated.remove(listener);
 			if (checkListeners()) {
 				switchToBackground();
@@ -2017,16 +2034,18 @@ public class XmppConnectionService extends Service {
 	}
 
 	public void setOnMucRosterUpdateListener(OnMucRosterUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			if (checkListeners()) {
 				switchToForeground();
 			}
-			this.mOnMucRosterUpdate.add(listener);
+			if (!this.mOnMucRosterUpdate.add(listener)) {
+				Log.w(Config.LOGTAG,listener.getClass().getName()+" is already registered as OnMucRosterListener");
+			}
 		}
 	}
 
 	public void removeOnMucRosterUpdateListener(final OnMucRosterUpdate listener) {
-		synchronized (this) {
+		synchronized (LISTENER_LOCK) {
 			this.mOnMucRosterUpdate.remove(listener);
 			if (checkListeners()) {
 				switchToBackground();
@@ -2039,6 +2058,7 @@ public class XmppConnectionService extends Service {
 				&& this.mOnConversationUpdates.size() == 0
 				&& this.mOnRosterUpdates.size() == 0
 				&& this.mOnCaptchaRequested.size() == 0
+				&& this.mOnMucRosterUpdate.size() == 0
 				&& this.mOnUpdateBlocklist.size() == 0
 				&& this.mOnShowErrorToasts.size() == 0
 				&& this.mOnKeyStatusUpdated.size() == 0);
@@ -3205,57 +3225,73 @@ public class XmppConnectionService extends Service {
 
 
 	public void showErrorToastInUi(int resId) {
-		for(OnShowErrorToast listener : this.mOnShowErrorToasts) {
-			listener.onShowErrorToast(resId);
+		synchronized (LISTENER_LOCK) {
+			for (OnShowErrorToast listener : this.mOnShowErrorToasts) {
+				listener.onShowErrorToast(resId);
+			}
 		}
 	}
 
 	public void updateConversationUi() {
-		for(OnConversationUpdate listener : this.mOnConversationUpdates) {
-			listener.onConversationUpdate();
+		synchronized (LISTENER_LOCK) {
+			for (OnConversationUpdate listener : this.mOnConversationUpdates) {
+				listener.onConversationUpdate();
+			}
 		}
 	}
 
 	public void updateAccountUi() {
-		for(OnAccountUpdate listener : this.mOnAccountUpdates) {
-			listener.onAccountUpdate();
+		synchronized (LISTENER_LOCK) {
+			for (OnAccountUpdate listener : this.mOnAccountUpdates) {
+				listener.onAccountUpdate();
+			}
 		}
 	}
 
 	public void updateRosterUi() {
-		for(OnRosterUpdate listener : this.mOnRosterUpdates) {
-			listener.onRosterUpdate();
+		synchronized (LISTENER_LOCK) {
+			for (OnRosterUpdate listener : this.mOnRosterUpdates) {
+				listener.onRosterUpdate();
+			}
 		}
 	}
 
 	public boolean displayCaptchaRequest(Account account, String id, Data data, Bitmap captcha) {
-		if (mOnCaptchaRequested.size() > 0) {
-			DisplayMetrics metrics = getApplicationContext().getResources().getDisplayMetrics();
-			Bitmap scaled = Bitmap.createScaledBitmap(captcha, (int) (captcha.getWidth() * metrics.scaledDensity),
-					(int) (captcha.getHeight() * metrics.scaledDensity), false);
-			for(OnCaptchaRequested listener : this.mOnCaptchaRequested) {
-				listener.onCaptchaRequested(account, id, data, scaled);
+		synchronized (LISTENER_LOCK) {
+			if (mOnCaptchaRequested.size() > 0) {
+				DisplayMetrics metrics = getApplicationContext().getResources().getDisplayMetrics();
+				Bitmap scaled = Bitmap.createScaledBitmap(captcha, (int) (captcha.getWidth() * metrics.scaledDensity),
+						(int) (captcha.getHeight() * metrics.scaledDensity), false);
+				for (OnCaptchaRequested listener : this.mOnCaptchaRequested) {
+					listener.onCaptchaRequested(account, id, data, scaled);
+				}
+				return true;
 			}
-			return true;
+			return false;
 		}
-		return false;
 	}
 
 	public void updateBlocklistUi(final OnUpdateBlocklist.Status status) {
-		for(OnUpdateBlocklist listener : this.mOnUpdateBlocklist) {
-			listener.OnUpdateBlocklist(status);
+		synchronized (LISTENER_LOCK) {
+			for (OnUpdateBlocklist listener : this.mOnUpdateBlocklist) {
+				listener.OnUpdateBlocklist(status);
+			}
 		}
 	}
 
 	public void updateMucRosterUi() {
-		for(OnMucRosterUpdate listener : this.mOnMucRosterUpdate) {
-			listener.onMucRosterUpdate();
+		synchronized (LISTENER_LOCK) {
+			for (OnMucRosterUpdate listener : this.mOnMucRosterUpdate) {
+				listener.onMucRosterUpdate();
+			}
 		}
 	}
 
 	public void keyStatusUpdated(AxolotlService.FetchStatus report) {
-		for(OnKeyStatusUpdated listener : this.mOnKeyStatusUpdated) {
-			listener.onKeyStatusUpdated(report);
+		synchronized (LISTENER_LOCK) {
+			for (OnKeyStatusUpdated listener : this.mOnKeyStatusUpdated) {
+				listener.onKeyStatusUpdated(report);
+			}
 		}
 	}
 
diff --git a/src/main/java/eu/siacs/conversations/ui/XmppActivity.java b/src/main/java/eu/siacs/conversations/ui/XmppActivity.java
index 9451a0fc3..3b747187c 100644
--- a/src/main/java/eu/siacs/conversations/ui/XmppActivity.java
+++ b/src/main/java/eu/siacs/conversations/ui/XmppActivity.java
@@ -88,7 +88,6 @@ public abstract class XmppActivity extends ActionBarActivity {
 	protected static final int REQUEST_BATTERY_OP = 0x49ff;
 	public XmppConnectionService xmppConnectionService;
 	public boolean xmppConnectionServiceBound = false;
-	protected final AtomicBoolean registeredListeners = new AtomicBoolean(false);
 
 	protected int mColorRed;
 
@@ -108,9 +107,7 @@ public abstract class XmppActivity extends ActionBarActivity {
 			XmppConnectionBinder binder = (XmppConnectionBinder) service;
 			xmppConnectionService = binder.getService();
 			xmppConnectionServiceBound = true;
-			if (registeredListeners.compareAndSet(false,true)) {
-				registerListeners();
-			}
+			registerListeners();
 			onBackendConnected();
 		}
 
@@ -212,9 +209,7 @@ public abstract class XmppActivity extends ActionBarActivity {
 				connectToBackend();
 			}
 		} else {
-			if (registeredListeners.compareAndSet(false,true)) {
-				this.registerListeners();
-			}
+			this.registerListeners();
 			this.onBackendConnected();
 		}
 	}
@@ -230,9 +225,7 @@ public abstract class XmppActivity extends ActionBarActivity {
 	protected void onStop() {
 		super.onStop();
 		if (xmppConnectionServiceBound) {
-			if (registeredListeners.compareAndSet(true, false)) {
-				this.unregisterListeners();
-			}
+			this.unregisterListeners();
 			unbindService(mConnection);
 			xmppConnectionServiceBound = false;
 		}