diff --git a/.php-cs-fixer.dist.php b/.php-cs-fixer.dist.php
new file mode 100644
index 0000000..d323b15
--- /dev/null
+++ b/.php-cs-fixer.dist.php
@@ -0,0 +1,19 @@
+<?php
+
+$config = new class extends Amp\CodeStyle\Config {
+    public function getRules(): array
+    {
+        $rules = parent::getRules();
+        $rules['declare_strict_types'] = false;
+
+        return $rules;
+    }
+};
+
+$config->getFinder()
+    ->in(__DIR__ . '/src')
+    ->in(__DIR__ . '/test');
+
+$config->setCacheFile(__DIR__ . '/.php_cs.cache');
+
+return $config;
diff --git a/.php_cs.dist b/.php_cs.dist
deleted file mode 100644
index cd06abc..0000000
--- a/.php_cs.dist
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php
-
-$config = new Amp\CodeStyle\Config();
-$config->getFinder()
-    ->in(__DIR__ . '/src')
-    ->in(__DIR__ . '/test');
-
-$cacheDir = getenv('TRAVIS') ? getenv('HOME') . '/.php-cs-fixer' : __DIR__;
-
-$config->setCacheFile($cacheDir . '/.php_cs.cache');
-
-return $config;
diff --git a/composer.json b/composer.json
index 677e41c..79cbd0d 100644
--- a/composer.json
+++ b/composer.json
@@ -22,7 +22,7 @@
     },
     "require-dev": {
         "amphp/amp": "^2",
-        "amphp/php-cs-fixer-config": "dev-master"
+        "amphp/php-cs-fixer-config": "^2"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/AsyncTestCase.php b/src/AsyncTestCase.php
index e16a11c..1cb0ac2 100644
--- a/src/AsyncTestCase.php
+++ b/src/AsyncTestCase.php
@@ -54,7 +54,7 @@ final public function runAsyncTest(...$args)
         if (!$this->setUpInvoked) {
             $this->fail(\sprintf(
                 '%s::setUp() overrides %s::setUp() without calling the parent method',
-                \str_replace("\0", '@', \get_class($this)), // replace NUL-byte in anonymous class name
+                \str_replace("\0", '@', static::class), // replace NUL-byte in anonymous class name
                 self::class
             ));
         }
@@ -129,7 +129,7 @@ private function runAsyncTestCycle(array $args): \Generator
         } catch (\Throwable $exception) {
             throw new \Error(\sprintf(
                 '%s::setUpAsync() failed',
-                \str_replace("\0", '@', \get_class($this)) // replace NUL-byte in anonymous class name
+                \str_replace("\0", '@', static::class) // replace NUL-byte in anonymous class name
             ), 0, $exception);
         }
 
@@ -144,7 +144,7 @@ private function runAsyncTestCycle(array $args): \Generator
         } catch (\Throwable $exception) {
             throw new \Error(\sprintf(
                 '%s::tearDownAsync() failed',
-                \str_replace("\0", '@', \get_class($this)) // replace NUL-byte in anonymous class name
+                \str_replace("\0", '@', static::class) // replace NUL-byte in anonymous class name
             ), 0, $exception);
         } finally {
             if (isset($testException)) {
@@ -256,11 +256,6 @@ final protected function createCallback(int $invocationCount, ?callable $returnC
 
     /**
      * Specialized Amp\call that stores the generator if present for debugging purposes.
-     *
-     * @param callable $callback
-     * @param mixed    ...$args
-     *
-     * @return Promise
      */
     private function call(callable $callback, ...$args): Promise
     {
diff --git a/test/AsyncTestCaseTest.php b/test/AsyncTestCaseTest.php
index 3725e8e..5384c4a 100644
--- a/test/AsyncTestCaseTest.php
+++ b/test/AsyncTestCaseTest.php
@@ -92,10 +92,6 @@ public function argumentSupportProvider(): array
     }
 
     /**
-     * @param string $foo
-     * @param int    $bar
-     * @param bool   $baz
-     *
      * @dataProvider argumentSupportProvider
      */
     public function testArgumentSupport(string $foo, int $bar, bool $baz)
@@ -106,11 +102,9 @@ public function testArgumentSupport(string $foo, int $bar, bool $baz)
     }
 
     /**
-     * @param string|null $value
-     *
      * @depends testReturningPromise
      */
-    public function testReturnValueFromDependentTest(string $value = null)
+    public function testReturnValueFromDependentTest(?string $value = null)
     {
         $this->assertSame('value', $value);
     }