diff --git a/build/psalm_bootstrap.php b/build/psalm_bootstrap.php
index cea4bc64be..03afd6da3d 100644
--- a/build/psalm_bootstrap.php
+++ b/build/psalm_bootstrap.php
@@ -49,6 +49,7 @@ $phpbb_class_loader->register();
 
 // Include files that require class loader to be initialized
 require_once $phpbb_root_path . 'includes/acp/auth.' . $phpEx;
+require_once $phpbb_root_path . 'includes/acp/acp_captcha.' . $phpEx;
 
 class phpbb_cache_container extends \Symfony\Component\DependencyInjection\Container
 {
diff --git a/phpBB/includes/acp/acp_captcha.php b/phpBB/includes/acp/acp_captcha.php
index b49c5ca0d3..ff9f515d32 100644
--- a/phpBB/includes/acp/acp_captcha.php
+++ b/phpBB/includes/acp/acp_captcha.php
@@ -23,6 +23,12 @@ class acp_captcha
 {
 	var $u_action;
 
+	/** @var string Template name */
+	public $tpl_name = 'acp_captcha';
+
+	/** @var string Page title language variable */
+	public $page_title = 'ACP_VC_SETTINGS';
+
 	function main($id, $mode)
 	{
 		global $user, $template, $phpbb_log, $request;
@@ -85,8 +91,6 @@ class acp_captcha
 				),
 			);
 
-			$this->tpl_name = 'acp_captcha';
-			$this->page_title = 'ACP_VC_SETTINGS';
 			$form_key = 'acp_captcha';
 			add_form_key($form_key);
 
diff --git a/phpBB/phpbb/captcha/factory.php b/phpBB/phpbb/captcha/factory.php
index dd44aca8bb..2e75ce8667 100644
--- a/phpBB/phpbb/captcha/factory.php
+++ b/phpBB/phpbb/captcha/factory.php
@@ -41,7 +41,7 @@ class factory
 	* Return a new instance of a given plugin
 	*
 	* @param $name
-	* @return object
+	* @return object|null
 	*/
 	public function get_instance($name)
 	{
diff --git a/phpBB/phpbb/captcha/gd.php b/phpBB/phpbb/captcha/gd.php
index 7f4d26ff00..308bc73e0b 100644
--- a/phpBB/phpbb/captcha/gd.php
+++ b/phpBB/phpbb/captcha/gd.php
@@ -1653,6 +1653,8 @@ class gd
 						),
 					),
 				);
+
+		/** @var 1|2|3 $config['captcha_gd_fonts'] */
 		return array(
 			'width'		=> 9,
 			'height'	=> 15,
diff --git a/phpBB/phpbb/captcha/gd_wave.php b/phpBB/phpbb/captcha/gd_wave.php
index 4f64e95a1d..e0801e7c50 100644
--- a/phpBB/phpbb/captcha/gd_wave.php
+++ b/phpBB/phpbb/captcha/gd_wave.php
@@ -205,7 +205,7 @@ class gd_wave
 				$x_index_old = intval(($x - 1) / $subdivision_factor);
 				$x_index_new = intval($x / $subdivision_factor);
 
-				if (!empty($plane[$y_index_new][$x_index_new]))
+				if ($plane[$y_index_new][$x_index_new])
 				{
 					$img_pos_cur[1]	+= $this->wave_height($x, $y, $subdivision_factor, 1) - 30 - $cur_height;
 					$color			= $colors[20];
@@ -213,10 +213,10 @@ class gd_wave
 				$img_pos_cur[1] = min($img_pos_cur[1], $img_y - 1);
 				$img_buffer[$buffer_cur][$x] = $img_pos_cur;
 
-				// Smooth the edges as much as possible by having not more than one low<->high traingle per square
+				// Smooth the edges as much as possible by having not more than one low<->high triangle per square
 				// Otherwise, just
-				$diag_down	= (empty($plane[$y_index_old][$x_index_old]) == empty($plane[$y_index_new][$x_index_new]));
-				$diag_up	= (empty($plane[$y_index_old][$x_index_new]) == empty($plane[$y_index_new][$x_index_old]));
+				$diag_down	= !$plane[$y_index_old][$x_index_old] && !$plane[$y_index_new][$x_index_new];
+				$diag_up	= !$plane[$y_index_old][$x_index_new] && !$plane[$y_index_new][$x_index_old];
 
 				// natural switching
 				$mode = ($x + $y) & 1;
diff --git a/phpBB/phpbb/captcha/plugins/qa.php b/phpBB/phpbb/captcha/plugins/qa.php
index f709c95353..811421a63c 100644
--- a/phpBB/phpbb/captcha/plugins/qa.php
+++ b/phpBB/phpbb/captcha/plugins/qa.php
@@ -39,6 +39,9 @@ class qa
 	*/
 	protected $service_name;
 
+	/** @var int Question ID */
+	protected $question = -1;
+
 	/**
 	* Constructor
 	*
@@ -450,7 +453,7 @@ class qa
 			'session_id'	=> (string) $user->session_id,
 			'lang_iso'		=> (string) $this->question_lang,
 			'confirm_type'	=> (int) $this->type,
-			'question_id'	=> (int) $this->question,
+			'question_id'	=> $this->question,
 		));
 		$db->sql_query($sql);
 
@@ -473,7 +476,7 @@ class qa
 		$this->solved = 0;
 
 		$sql = 'UPDATE ' . $this->table_qa_confirm . '
-			SET question_id = ' . (int) $this->question . "
+			SET question_id = ' . $this->question . "
 			WHERE confirm_id = '" . $db->sql_escape($this->confirm_id) . "'
 				AND session_id = '" . $db->sql_escape($user->session_id) . "'";
 		$db->sql_query($sql);
@@ -493,7 +496,7 @@ class qa
 		$this->solved = 0;
 
 		$sql = 'UPDATE ' . $this->table_qa_confirm . '
-			SET question_id = ' . (int) $this->question . ",
+			SET question_id = ' . $this->question . ",
 				attempts = attempts + 1
 			WHERE confirm_id = '" . $db->sql_escape($this->confirm_id) . "'
 				AND session_id = '" . $db->sql_escape($user->session_id) . "'";
@@ -553,7 +556,7 @@ class qa
 
 		if ($row)
 		{
-			$this->question = $row['question_id'];
+			$this->question = (int) $row['question_id'];
 
 			$this->attempts = $row['attempts'];
 			$this->question_strict = $row['strict'];
@@ -576,7 +579,7 @@ class qa
 
 		$sql = 'SELECT answer_text
 			FROM ' . $this->table_captcha_answers . '
-			WHERE question_id = ' . (int) $this->question;
+			WHERE question_id = ' . $this->question;
 		$result = $db->sql_query($sql);
 
 		while ($row = $db->sql_fetchrow($result))