diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index fdb2697..8dfb311 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -9,7 +9,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        php: [ '5.5.9', '5.6', '7.1','7.2', '7.3', '7.4', '8.0', '8.1', '8.2' ]
+        php: [ '5.5.9', '5.6', '7.1','7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3' ]
         stability: [ prefer-stable ]
 
     name: PHP ${{ matrix.php }} - ${{ matrix.stability }}
diff --git a/resources/converter.php b/resources/converter.php
index c4fb615..7181b3c 100644
--- a/resources/converter.php
+++ b/resources/converter.php
@@ -4,15 +4,20 @@
 
 use Recca0120\Twzipcode\Storages\File;
 
+set_error_handler(static function ($severity, $message, $file, $line) {
+    throw new ErrorException($message, $severity, $severity, $file, $line);
+});
+
 $start = microtime(true);
 $file = __DIR__.'/Zip32_utf8_10501_1.zip';
 
 // https://data.gov.tw/dataset/5948
-$url = 'https://quality.data.gov.tw/dq_download_csv.php?nid=5948&md5_url=b7ce2082883f6b680810828799d4c32e';
+$url = 'https://quality.data.gov.tw/dq_download_csv.php?nid=5948&md5_url=e1f6004ad33eb3ff3a824fb992a4b01a';
 
 if (file_exists($file) === false) {
     touch($file);
     $contents = file_get_contents($url);
+
     $encoding = mb_detect_encoding($contents, ['UCS-2LE', 'BIG5', 'UTF-8']);
     if ($encoding !== 'UTF-8') {
         $contents = mb_convert_encoding($contents, 'UTF-8', $encoding);
@@ -20,6 +25,10 @@
     $contents = preg_replace("/^\xEF\xBB\xBF/", '', $contents);
     $contents = trim(str_replace('Zip5,City,Area,Road,Scope', '', $contents));
 
+    if (strpos('Zip5,City,Area,Road,Scope', $contents) === false) {
+        throw new RuntimeException($contents);
+    }
+
     $zip = new ZipArchive;
     $zip->open($file, ZipArchive::OVERWRITE);
     $zip->addFromString(pathinfo($file, PATHINFO_FILENAME).'.csv', $contents);
diff --git a/src/Storages/File.php b/src/Storages/File.php
index e392e34..433f111 100644
--- a/src/Storages/File.php
+++ b/src/Storages/File.php
@@ -42,7 +42,7 @@ public function zip3(Address $address)
 
         foreach ([2, 1] as $value) {
             $flat = $address->flat($value);
-            if (isset(self::$cached['zip3'][$flat])) {
+            if (! empty(self::$cached['zip3'][$flat])) {
                 return self::$cached['zip3'][$flat];
             }
         }
@@ -65,11 +65,11 @@ function ($zipcode, $county, $district, $rules) use (&$zip5, &$zip3) {
                     return new Rule($rule);
                 }, $rules));
 
-                if (isset($zip3[$county]) === false) {
+                if (empty($zip3[$county])) {
                     $zip3[$county] = substr($zipcode, 0, 1);
                 }
 
-                if (isset($zip3[$county.$district]) === false) {
+                if (empty($zip3[$county.$district])) {
                     $zip3[$county.$district] = substr($zipcode, 0, 3);
                 }
             });
@@ -88,7 +88,7 @@ public function rules($zip3)
     {
         $this->restore('zip5');
 
-        return isset(self::$cached['zip5'][$zip3]) === true
+        return ! empty(self::$cached['zip5'][$zip3])
             ? new JArray($this->decompress(self::$cached['zip5'][$zip3]))
             : new JArray([]);
     }
@@ -168,9 +168,9 @@ private function prepareSource($source)
         $results = [];
         $rules = preg_split('/\n|\r\n$/', $source);
         foreach ($rules as $rule) {
-            if (empty(trim($rule)) === false) {
+            if (! empty(trim($rule))) {
                 list($zipcode, $county, $district) = explode(',', $rule);
-                $zip3 = isset($tricks[$county.$district]) === true
+                $zip3 = ! empty($tricks[$county.$district])
                     ? $tricks[$county.$district]
                     : substr($zipcode, 0, 3);
                 $results[$county][$district][$zip3][] = $rule;