diff --git a/phpBB/includes/acp/auth.php b/phpBB/includes/acp/auth.php
index 905e981cdc..52c45499b2 100644
--- a/phpBB/includes/acp/auth.php
+++ b/phpBB/includes/acp/auth.php
@@ -1113,6 +1113,11 @@ class auth_admin extends \phpbb\auth\auth
 		@reset($category_array);
 		while (list($cat, $cat_array) = each($category_array))
 		{
+			if (!$phpbb_permissions->category_defined($cat))
+			{
+				continue;
+			}
+
 			$template->assign_block_vars($tpl_cat, array(
 				'S_YES'		=> ($cat_array['S_YES'] && !$cat_array['S_NEVER'] && !$cat_array['S_NO']) ? true : false,
 				'S_NEVER'	=> ($cat_array['S_NEVER'] && !$cat_array['S_YES'] && !$cat_array['S_NO']) ? true : false,
@@ -1139,6 +1144,11 @@ class auth_admin extends \phpbb\auth\auth
 			@reset($cat_array['permissions']);
 			while (list($permission, $allowed) = each($cat_array['permissions']))
 			{
+				if (!$phpbb_permissions->permission_defined($permission))
+				{
+					continue;
+				}
+
 				if ($s_view)
 				{
 					$template->assign_block_vars($tpl_cat . '.' . $tpl_mask, array(
diff --git a/phpBB/phpbb/permissions.php b/phpBB/phpbb/permissions.php
index 82f59b5c20..42bbe443d1 100644
--- a/phpBB/phpbb/permissions.php
+++ b/phpBB/phpbb/permissions.php
@@ -159,6 +159,28 @@ class permissions
 		return (isset($this->permissions[$permission]['cat'])) ? $this->permissions[$permission]['cat'] : 'misc';
 	}
 
+	/**
+	* Checks if a category has been defined
+	*
+	* @param	string	$category	Identifier of the category
+	* @return	bool	True if the category is defined, false otherwise
+	*/
+	public function category_defined($category)
+	{
+		return isset($this->categories[$category]);
+	}
+
+	/**
+	* Checks if a permission has been defined
+	*
+	* @param	string	$permission	Identifier of the permission
+	* @return	bool	True if the permission is defined, false otherwise
+	*/
+	public function permission_defined($permission)
+	{
+		return isset($this->permissions[$permission]);
+	}
+
 	/**
 	* Returns the language string of a permission
 	*