diff --git a/src/lib/adblock/adblockmanager.cpp b/src/lib/adblock/adblockmanager.cpp
index 98cefe81c..9f7f6d6a2 100644
--- a/src/lib/adblock/adblockmanager.cpp
+++ b/src/lib/adblock/adblockmanager.cpp
@@ -34,6 +34,7 @@
 #include <QTimer>
 #include <QMessageBox>
 #include <QUrlQuery>
+#include <QMutexLocker>
 
 //#define ADBLOCK_DEBUG
 
@@ -80,6 +81,14 @@ void AdBlockManager::setEnabled(bool enabled)
 
     load();
     mApp->reloadUserStyleSheet();
+
+    QMutexLocker locker(&m_mutex);
+
+    if (m_enabled) {
+        m_matcher->update();
+    } else {
+        m_matcher->clear();
+    }
 }
 
 QList<AdBlockSubscription*> AdBlockManager::subscriptions() const
@@ -89,6 +98,8 @@ QList<AdBlockSubscription*> AdBlockManager::subscriptions() const
 
 bool AdBlockManager::block(QWebEngineUrlRequestInfo &request)
 {
+    QMutexLocker locker(&m_mutex);
+
 #ifdef ADBLOCK_DEBUG
     QElapsedTimer timer;
     timer.start();
@@ -201,13 +212,15 @@ AdBlockSubscription* AdBlockManager::addSubscription(const QString &title, const
 
     m_subscriptions.insert(m_subscriptions.count() - 1, subscription);
     connect(subscription, SIGNAL(subscriptionUpdated()), mApp, SLOT(reloadUserStyleSheet()));
-    connect(subscription, SIGNAL(subscriptionChanged()), m_matcher, SLOT(update()));
+    connect(subscription, SIGNAL(subscriptionChanged()), this, SLOT(updateMatcher()));
 
     return subscription;
 }
 
 bool AdBlockManager::removeSubscription(AdBlockSubscription* subscription)
 {
+    QMutexLocker locker(&m_mutex);
+
     if (!m_subscriptions.contains(subscription) || !subscription->canBeRemoved()) {
         return false;
     }
@@ -236,6 +249,8 @@ AdBlockCustomList* AdBlockManager::customList() const
 
 void AdBlockManager::load()
 {
+    QMutexLocker locker(&m_mutex);
+
     if (m_loaded) {
         return;
     }
@@ -310,7 +325,7 @@ void AdBlockManager::load()
         subscription->loadSubscription(m_disabledRules);
 
         connect(subscription, SIGNAL(subscriptionUpdated()), mApp, SLOT(reloadUserStyleSheet()));
-        connect(subscription, SIGNAL(subscriptionChanged()), m_matcher, SLOT(update()));
+        connect(subscription, SIGNAL(subscriptionChanged()), this, SLOT(updateMatcher()));
     }
 
     if (lastUpdate.addDays(5) < QDateTime::currentDateTime()) {
@@ -327,6 +342,13 @@ void AdBlockManager::load()
     mApp->networkManager()->installUrlInterceptor(m_interceptor);
 }
 
+void AdBlockManager::updateMatcher()
+{
+    QMutexLocker locker(&m_mutex);
+
+    m_matcher->update();
+}
+
 void AdBlockManager::updateAllSubscriptions()
 {
     foreach (AdBlockSubscription* subscription, m_subscriptions) {
diff --git a/src/lib/adblock/adblockmanager.h b/src/lib/adblock/adblockmanager.h
index 3c627eaa8..a0887101f 100644
--- a/src/lib/adblock/adblockmanager.h
+++ b/src/lib/adblock/adblockmanager.h
@@ -1,6 +1,6 @@
 /* ============================================================
-* QupZilla - WebKit based browser
-* Copyright (C) 2010-2016 David Rosca <nowrep@gmail.com>
+* QupZilla - Qt web browser
+* Copyright (C) 2010-2017 David Rosca <nowrep@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
@@ -21,6 +21,7 @@
 #include <QObject>
 #include <QStringList>
 #include <QPointer>
+#include <QMutex>
 
 #include "qzcommon.h"
 
@@ -79,6 +80,7 @@ public slots:
     void setEnabled(bool enabled);
     void showRule();
 
+    void updateMatcher();
     void updateAllSubscriptions();
 
     AdBlockDialog* showDialog();
@@ -96,6 +98,7 @@ private:
 
     AdBlockUrlInterceptor *m_interceptor;
     QPointer<AdBlockDialog> m_adBlockDialog;
+    QMutex m_mutex;
 };
 
 #endif // ADBLOCKMANAGER_H
diff --git a/src/lib/adblock/adblockmatcher.cpp b/src/lib/adblock/adblockmatcher.cpp
index 51a01d1b8..98581d906 100644
--- a/src/lib/adblock/adblockmatcher.cpp
+++ b/src/lib/adblock/adblockmatcher.cpp
@@ -1,6 +1,6 @@
 /* ============================================================
-* QupZilla - WebKit based browser
-* Copyright (C) 2014  David Rosca <nowrep@gmail.com>
+* QupZilla - Qt web browser
+* Copyright (C) 2014-2017 David Rosca <nowrep@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
@@ -24,7 +24,6 @@ AdBlockMatcher::AdBlockMatcher(AdBlockManager* manager)
     : QObject(manager)
     , m_manager(manager)
 {
-    connect(manager, SIGNAL(enabledChanged(bool)), this, SLOT(enabledChanged(bool)));
 }
 
 AdBlockMatcher::~AdBlockMatcher()
@@ -218,11 +217,3 @@ void AdBlockMatcher::clear()
     qDeleteAll(m_createdRules);
     m_createdRules.clear();
 }
-
-void AdBlockMatcher::enabledChanged(bool enabled)
-{
-    if (enabled)
-        update();
-    else
-        clear();
-}
diff --git a/src/lib/adblock/adblockmatcher.h b/src/lib/adblock/adblockmatcher.h
index 49502d191..12ff2318d 100644
--- a/src/lib/adblock/adblockmatcher.h
+++ b/src/lib/adblock/adblockmatcher.h
@@ -1,6 +1,6 @@
 /* ============================================================
-* QupZilla - WebKit based browser
-* Copyright (C) 2014  David Rosca <nowrep@gmail.com>
+* QupZilla - Qt web browser
+* Copyright (C) 2014-2017 David Rosca <nowrep@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
@@ -48,9 +48,6 @@ public slots:
     void update();
     void clear();
 
-private slots:
-    void enabledChanged(bool enabled);
-
 private:
     AdBlockManager* m_manager;