diff --git a/docker-compose.yml b/docker-compose.yml
index d507bc4..b4ee982 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -90,7 +90,3 @@ services:
 
 volumes:
   wordpress:
-
-networks:
-  default:
-    name: swoole-library-network
diff --git a/src/core/MultibyteStringObject.php b/src/core/MultibyteStringObject.php
index e45b847..fc15654 100644
--- a/src/core/MultibyteStringObject.php
+++ b/src/core/MultibyteStringObject.php
@@ -18,36 +18,24 @@ public function length(): int
         return mb_strlen($this->string);
     }
 
-    /**
-     * @return false|int
-     */
-    public function indexOf(string $needle, int $offset = 0, ?string $encoding = null)
+    public function indexOf(string $needle, int $offset = 0, ?string $encoding = null): false|int
     {
-        return mb_strpos($this->string, ...func_get_args());
+        return mb_strpos($this->string, $needle, $offset, $encoding);
     }
 
-    /**
-     * @return false|int
-     */
-    public function lastIndexOf(string $needle, int $offset = 0, ?string $encoding = null)
+    public function lastIndexOf(string $needle, int $offset = 0, ?string $encoding = null): false|int
     {
-        return mb_strrpos($this->string, ...func_get_args());
+        return mb_strrpos($this->string, $needle, $offset, $encoding);
     }
 
-    /**
-     * @return false|int
-     */
-    public function pos(string $needle, int $offset = 0, ?string $encoding = null)
+    public function pos(string $needle, int $offset = 0, ?string $encoding = null): false|int
     {
-        return mb_strpos($this->string, ...func_get_args());
+        return mb_strpos($this->string, $needle, $offset, $encoding);
     }
 
-    /**
-     * @return false|int
-     */
-    public function rpos(string $needle, int $offset = 0, ?string $encoding = null)
+    public function rpos(string $needle, int $offset = 0, ?string $encoding = null): false|int
     {
-        return mb_strrpos($this->string, ...func_get_args());
+        return mb_strrpos($this->string, $needle, $offset, $encoding);
     }
 
     /**
diff --git a/src/core/NameResolver.php b/src/core/NameResolver.php
index b21c9ca..488b643 100644
--- a/src/core/NameResolver.php
+++ b/src/core/NameResolver.php
@@ -77,7 +77,7 @@ public function lookup(string $name)
     /**
      * !!! The host MUST BE IP ADDRESS
      */
-    protected function checkServerUrl(mixed $url)
+    protected function checkServerUrl(string $url)
     {
         $info = parse_url($url);
         if (empty($info['scheme']) or empty($info['host'])) {
@@ -102,11 +102,7 @@ protected function checkServerUrl(mixed $url)
         $this->info    = $info;
     }
 
-    /**
-     * @param $r ClientProxy
-     * @return bool
-     */
-    protected function checkResponse($r, mixed $url)
+    protected function checkResponse(?ClientProxy $r, string $url): bool
     {
         if (empty($r)) {
             throw new Exception("failed to request URL({$url})");
diff --git a/src/core/StringObject.php b/src/core/StringObject.php
index 44a1ce0..f3ef973 100644
--- a/src/core/StringObject.php
+++ b/src/core/StringObject.php
@@ -13,10 +13,7 @@
 
 class StringObject implements \Stringable
 {
-    /**
-     * @var string
-     */
-    protected $string;
+    protected string $string;
 
     /**
      * StringObject constructor.
@@ -41,36 +38,24 @@ public function length(): int
         return strlen($this->string);
     }
 
-    /**
-     * @return false|int
-     */
-    public function indexOf(string $needle, int $offset = 0)
+    public function indexOf(string $needle, int $offset = 0): false|int
     {
-        return strpos($this->string, ...(string) func_get_args());
+        return strpos($this->string, $needle, $offset);
     }
 
-    /**
-     * @return false|int
-     */
-    public function lastIndexOf(string $needle, int $offset = 0)
+    public function lastIndexOf(string $needle, int $offset = 0): false|int
     {
-        return strrpos($this->string, ...(string) func_get_args());
+        return strrpos($this->string, $needle, $offset);
     }
 
-    /**
-     * @return false|int
-     */
-    public function pos(string $needle, int $offset = 0)
+    public function pos(string $needle, int $offset = 0): false|int
     {
-        return strpos($this->string, ...(string) func_get_args());
+        return strpos($this->string, $needle, $offset);
     }
 
-    /**
-     * @return false|int
-     */
-    public function rpos(string $needle, int $offset = 0)
+    public function rpos(string $needle, int $offset = 0): false|int
     {
-        return strrpos($this->string, ...(string) func_get_args());
+        return strrpos($this->string, $needle, $offset);
     }
 
     /**
diff --git a/tests/unit/Coroutine/FunctionTest.php b/tests/unit/Coroutine/FunctionTest.php
index 6298af4..e781a90 100644
--- a/tests/unit/Coroutine/FunctionTest.php
+++ b/tests/unit/Coroutine/FunctionTest.php
@@ -38,7 +38,11 @@ public function testBatchTimeout()
                 },
             ], 0.1);
             Runtime::setHookFlags(0);
-            self::assertEqualsWithDelta(microtime(true), $start + 0.11, 0.01, 'Tasks in the batch take about 0.10 to 0.12 second in total to finish.');
+            self::assertThat(
+                microtime(true),
+                self::logicalAnd(self::greaterThan($start + 0.09), self::lessThan($start + 0.15)),
+                'Tasks in the batch take 0.10+ second to finish.'
+            );
             $this->assertEquals(count($results), 4);
 
             $this->assertEquals($results['gethostbyname'], gethostbyname('localhost'));