diff --git a/framework/core/src/Core/CoreServiceProvider.php b/framework/core/src/Core/CoreServiceProvider.php
index 2cc1b4c44..d6c3f7de2 100644
--- a/framework/core/src/Core/CoreServiceProvider.php
+++ b/framework/core/src/Core/CoreServiceProvider.php
@@ -106,6 +106,7 @@ class CoreServiceProvider extends AbstractServiceProvider
 
         $events->subscribe('Flarum\Core\Listener\DiscussionMetadataUpdater');
         $events->subscribe('Flarum\Core\Listener\UserMetadataUpdater');
+        $events->subscribe('Flarum\Core\Listener\ExtensionValidator');
         $events->subscribe('Flarum\Core\Listener\EmailConfirmationMailer');
         $events->subscribe('Flarum\Core\Listener\DiscussionRenamedNotifier');
 
diff --git a/framework/core/src/Core/Listener/ExtensionValidator.php b/framework/core/src/Core/Listener/ExtensionValidator.php
new file mode 100644
index 000000000..2f25af476
--- /dev/null
+++ b/framework/core/src/Core/Listener/ExtensionValidator.php
@@ -0,0 +1,42 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Core\Listener;
+
+use Flarum\Event\ExtensionWillBeDisabled;
+use Flarum\Http\Exception\MethodNotAllowedException;
+use Illuminate\Contracts\Events\Dispatcher;
+
+class ExtensionValidator
+{
+    /**
+     * @param Dispatcher $events
+     */
+    public function subscribe(Dispatcher $events)
+    {
+        $events->listen(ExtensionWillBeDisabled::class, [$this, 'whenExtensionWillBeDisabled']);
+    }
+
+    /**
+     * @param ExtensionWillBeDisabled $event
+     * @throws MethodNotAllowedException
+     */
+    public function whenExtensionWillBeDisabled(ExtensionWillBeDisabled $event)
+    {
+        if (in_array('flarum-locale', $event->extension->extra)) {
+            $default_locale = $this->app->make('flarum.settings')->get('default_locale');
+            $locale = array_get($event->extension->extra, 'flarum-locale.code');
+            if ($locale === $default_locale) {
+                throw new MethodNotAllowedException('You cannot disable the default language pack!');
+            }
+        }
+    }
+}
diff --git a/framework/core/src/Event/ExtensionWillBeDisabled.php b/framework/core/src/Event/ExtensionWillBeDisabled.php
new file mode 100644
index 000000000..6df58a41c
--- /dev/null
+++ b/framework/core/src/Event/ExtensionWillBeDisabled.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Event;
+
+use Flarum\Extension\Extension;
+
+class ExtensionWillBeDisabled
+{
+    /**
+     * @var string
+     */
+    protected $extension;
+
+    /**
+     * @param Extension $extension
+     */
+    public function __construct(Extension $extension)
+    {
+        $this->extension = $extension;
+    }
+}
diff --git a/framework/core/src/Event/ExtensionWillBeEnabled.php b/framework/core/src/Event/ExtensionWillBeEnabled.php
new file mode 100644
index 000000000..e0a9214e3
--- /dev/null
+++ b/framework/core/src/Event/ExtensionWillBeEnabled.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Event;
+
+use Flarum\Extension\Extension;
+
+class ExtensionWillBeEnabled
+{
+    /**
+     * @var string
+     */
+    protected $extension;
+
+    /**
+     * @param Extension $extension
+     */
+    public function __construct(Extension $extension)
+    {
+        $this->extension = $extension;
+    }
+}
diff --git a/framework/core/src/Extension/ExtensionManager.php b/framework/core/src/Extension/ExtensionManager.php
index 9ea1e9e2d..f0e62838c 100644
--- a/framework/core/src/Extension/ExtensionManager.php
+++ b/framework/core/src/Extension/ExtensionManager.php
@@ -15,6 +15,8 @@ use Flarum\Database\Migrator;
 use Flarum\Event\ExtensionWasDisabled;
 use Flarum\Event\ExtensionWasEnabled;
 use Flarum\Event\ExtensionWasUninstalled;
+use Flarum\Event\ExtensionWillBeDisabled;
+use Flarum\Event\ExtensionWillBeEnabled;
 use Flarum\Foundation\Application;
 use Flarum\Settings\SettingsRepositoryInterface;
 use Illuminate\Contracts\Events\Dispatcher;
@@ -112,6 +114,8 @@ class ExtensionManager
     {
         if (! $this->isEnabled($name)) {
             $extension = $this->getExtension($name);
+            
+            $this->dispatcher->fire(new ExtensionWillBeEnabled($extension));
 
             $enabled = $this->getEnabled();
 
@@ -139,9 +143,11 @@ class ExtensionManager
         $enabled = $this->getEnabled();
 
         if (($k = array_search($name, $enabled)) !== false) {
-            unset($enabled[$k]);
-
             $extension = $this->getExtension($name);
+            
+            $this->dispatcher->fire(new ExtensionWillBeDisabled($extension));
+
+            unset($enabled[$k]);
 
             $this->setEnabled($enabled);