diff --git a/assets/zhttfs/1.otf b/assets/zhttfs/1.otf
new file mode 100644
index 0000000..886f82f
Binary files /dev/null and b/assets/zhttfs/1.otf differ
diff --git a/assets/zhttfs/1.ttf b/assets/zhttfs/1.ttf
deleted file mode 100644
index 1c14f7f..0000000
Binary files a/assets/zhttfs/1.ttf and /dev/null differ
diff --git a/src/Captcha.php b/src/Captcha.php
index 1689344..56676af 100644
--- a/src/Captcha.php
+++ b/src/Captcha.php
@@ -192,7 +192,7 @@ public function create(string $config = null, bool $api = false): Response
             $dir  = dir($ttfPath);
             $ttfs = [];
             while (false !== ($file = $dir->read())) {
-                if ('.' != $file[0] && substr($file, -4) == '.ttf') {
+                if (substr($file, -4) == '.ttf' || substr($file, -4) == '.otf') {
                     $ttfs[] = $file;
                 }
             }