diff --git a/inc/Service/SecureimageCaptchaQuery.php b/inc/Service/SecureimageCaptchaQuery.php
index 90dcdbb6..0b33c059 100644
--- a/inc/Service/SecureimageCaptchaQuery.php
+++ b/inc/Service/SecureimageCaptchaQuery.php
@@ -38,6 +38,8 @@ class SecureImageCaptchaQuery {
 		];
 
 		$ret = $this->http->requestGet($this->domain . '/' . $this->provider_check, $data);
-		return $ret === '1';
+		$resp = \json_decode($ret, true, 16, \JSON_THROW_ON_ERROR);
+
+		return isset($resp['success']) && $resp['success'];
 	}
 }
diff --git a/inc/config.php b/inc/config.php
index feecaca9..5f9b7130 100644
--- a/inc/config.php
+++ b/inc/config.php
@@ -393,7 +393,9 @@
 			'new_thread_capt' => false,
 			// Securimage customization options
 			// https://github.com/dapphp/securimage/blob/nextgen/examples/securimage_show_example.php#L49
-			'securimage_options' => ['send_headers' => false, 'no_exit' => true]
+			'securimage_options' => ['send_headers' => false, 'no_exit' => true],
+			// Captcha expires (in seconds)
+			'expires_in' => 320
 		]
 	];
 
diff --git a/securimage.php b/securimage.php
index f5e5a81c..8ebfa154 100644
--- a/securimage.php
+++ b/securimage.php
@@ -1,69 +1,88 @@
 <?php
 require_once('inc/bootstrap.php');
-$expires_in = 120;
 
-function rand_string($length, $charset) {
-	$ret = "";
+function rand_string(int $length, string $charset): string {
+	$ret = '';
 	while ($length--) {
 		$ret .= mb_substr($charset, rand(0, mb_strlen($charset, 'utf-8')-1), 1, 'utf-8');
 	}
 	return $ret;
 }
 
-function cleanup() {
-	global $expires_in;
+function cleanup(int $expires_in): void {
 	prepare("DELETE FROM `captchas` WHERE `created_at` < ?")->execute([time() - $expires_in]);
 }
 
+function handleGetRequestCaptcha(array $config): void {
+	$extra = $config['captcha']['native']['extra'];
+	$cookie = rand_string(20, $extra);
 
-$mode = @$_GET['mode'];
-switch ($mode) {
+	$securimage = new Securimage($config['captcha']['native']['securimage_options']);
+	$securimage->createCode();
+
+	ob_start();
+	$securimage->show();
+	$rawImage = ob_get_clean();
+
+	$base64Image = 'data:image/png;base64,' . base64_encode($rawImage);
+	$html = '<img src="' . $base64Image . '">';
+	$captchaCode = $securimage->getCode();
+
+	prepare("INSERT INTO `captchas` (`cookie`, `extra`, `text`, `created_at`) VALUES (?, ?, ?, ?)")
+		->execute([$cookie, $extra, $captchaCode->code_display, $captchaCode->creationTime]);
+
+	if (isset($_GET['raw'])) {
+		$_SESSION['captcha_cookie'] = $cookie;
+		header('Content-Type: image/png');
+		echo $rawImage;
+	} else {
+		header("Content-Type: application/json");
+		echo json_encode([
+			"cookie" => $cookie,
+			"captchahtml" => $html,
+			"expires_in" => $config['captcha']['native']['expires_in'],
+		]);
+	}
+}
+
+function handleCheckRequestCaptcha(int $expires_in): void {
+	cleanup($expires_in);
+
+	$cookie = $_GET['cookie'] ?? null;
+	$text = $_GET['text'] ?? null;
+
+	if (!$cookie || !$text) {
+		echo json_encode(["success" => false]);
+		return;
+	}
+
+	$query = prepare("SELECT * FROM `captchas` WHERE `cookie` = ?");
+	$query->execute([$cookie]);
+	$captchaData = $query->fetchAll();
+
+	if (!$captchaData) {
+		echo json_encode(["success" => false]);
+		return;
+	}
+
+	prepare("DELETE FROM `captchas` WHERE `cookie` = ?")->execute([$cookie]);
+
+	$isSuccessful = $captchaData[0]['text'] === $text;
+	echo json_encode(["success" => $isSuccessful]);
+}
+
+$mode = $_GET['mode'] ?? null;
+
+switch($mode) {
 	case 'get':
-		header("Content-type: application/json");
-		$extra = $config['captcha']['native']['extra'];
-		$cookie = rand_string(20, $extra);
-		$i = new Securimage($config['captcha']['native']['securimage_options']);
-		$i->createCode();
-		ob_start();
-		$i->show();
-		$rawimg = ob_get_contents();
-		$b64img = 'data:image/png;base64,'.base64_encode($rawimg);
-		$html = '<img src="'.$b64img.'">';
-		ob_end_clean();
-		$cdata = $i->getCode();
-		$query = prepare("INSERT INTO `captchas` (`cookie`, `extra`, `text`, `created_at`) VALUES (?, ?, ?, ?)");
-		$query->execute([$cookie, $extra, $cdata->code_display, $cdata->creationTime]);
-		if (isset($_GET['raw'])) {
-			$_SESSION['captcha_cookie'] = $cookie;
-			header('Content-Type: image/png');
-			echo $rawimg;
-		} else {
-			echo json_encode(["cookie" => $cookie, "captchahtml" => $html, "expires_in" => $expires_in]);
-		}
+		handleGetRequestCaptcha($config);
 		break;
 	case 'check':
-		cleanup();
-		if (!isset ($_GET['mode']) || !isset ($_GET['cookie']) || !isset ($_GET['text'])) {
-			die();
-		}
-
-		$query = prepare("SELECT * FROM `captchas` WHERE `cookie` = ?");
-		$query->execute([$_GET['cookie']]);
-
-		$ary = $query->fetchAll();
-
-		if (!$ary) { // captcha expired
-			echo "0";
-			break;
-		} else {
-			$query = prepare("DELETE FROM `captchas` WHERE `cookie` = ?");
-			$query->execute([$_GET['cookie']]);
-		}
-
-		if ($ary[0]['text'] !== $_GET['text']) {
-			echo "0";
-		} else {
-			echo "1";
-		}
+		handleCheckRequestCaptcha($config['captcha']['native']['expires_in']);
 		break;
-}
+	case '':
+	default:
+		http_response_code(400);
+		echo json_encode(["success" => false, "error" => "Invalid mode"]);
+		break;
+}
\ No newline at end of file