diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a398ff9..bfddda3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,10 +7,11 @@ on:
 jobs:
   PHPUnit:
     name: PHPUnit (PHP ${{ matrix.php }})
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     strategy:
       matrix:
         php:
+          - 8.4
           - 8.3
           - 8.2
           - 8.1
@@ -24,7 +25,7 @@ jobs:
       - uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
-          coverage: xdebug
+          coverage: ${{ matrix.php < 8.0 && 'xdebug' || 'pcov' }}
           ini-file: development
       - run: composer install
       - run: vendor/bin/phpunit --coverage-text
@@ -34,10 +35,11 @@ jobs:
 
   PHPStan:
     name: PHPStan (PHP ${{ matrix.php }})
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     strategy:
       matrix:
         php:
+          - 8.4
           - 8.3
           - 8.2
           - 8.1
diff --git a/composer.json b/composer.json
index 5d1e277..e2e6ffc 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,7 @@
         "php": ">=7.1.0"
     },
     "require-dev": {
-        "phpstan/phpstan": "1.10.39 || 1.4.10",
+        "phpstan/phpstan": "1.12.19 || 1.4.10",
         "phpunit/phpunit": "^9.6 || ^7.5"
     },
     "autoload": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 33ea968..4305518 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -28,5 +28,8 @@
         <ini name="assert.active" value="1" />
         <ini name="assert.exception" value="1" />
         <ini name="assert.bail" value="0" />
+        <env name="XDEBUG_MODE" value="off"/>
+        <ini name="pcov.enabled" value="1"/>
+        <ini name="xdebug.mode" value="off"/>
     </php>
 </phpunit>
diff --git a/src/Internal/FulfilledPromise.php b/src/Internal/FulfilledPromise.php
index 8664ffd..ec693a3 100644
--- a/src/Internal/FulfilledPromise.php
+++ b/src/Internal/FulfilledPromise.php
@@ -56,9 +56,14 @@ public function catch(callable $onRejected): PromiseInterface
         return $this;
     }
 
+    /**
+     * @param callable(): (void|PromiseInterface<void>) $onFulfilledOrRejected
+     * @return PromiseInterface<T>
+     */
     public function finally(callable $onFulfilledOrRejected): PromiseInterface
     {
         return $this->then(function ($value) use ($onFulfilledOrRejected): PromiseInterface {
+            /** @var T $value */
             return resolve($onFulfilledOrRejected())->then(function () use ($value) {
                 return $value;
             });
diff --git a/src/Promise.php b/src/Promise.php
index 4ac2700..11e928b 100644
--- a/src/Promise.php
+++ b/src/Promise.php
@@ -94,9 +94,14 @@ public function catch(callable $onRejected): PromiseInterface
         });
     }
 
+    /**
+     * @param callable(): (void|PromiseInterface<void>) $onFulfilledOrRejected
+     * @return PromiseInterface<T>
+     */
     public function finally(callable $onFulfilledOrRejected): PromiseInterface
     {
         return $this->then(static function ($value) use ($onFulfilledOrRejected): PromiseInterface {
+            /** @var T $value */
             return resolve($onFulfilledOrRejected())->then(function () use ($value) {
                 return $value;
             });
diff --git a/tests/FunctionSetRejectionHandlerThatTriggersDefaultHandlerShouldTerminateProgramForUnhandled.phpt b/tests/FunctionSetRejectionHandlerThatTriggersDefaultHandlerShouldTerminateProgramForUnhandled.phpt
index 14b5c7c..8531f6d 100644
--- a/tests/FunctionSetRejectionHandlerThatTriggersDefaultHandlerShouldTerminateProgramForUnhandled.phpt
+++ b/tests/FunctionSetRejectionHandlerThatTriggersDefaultHandlerShouldTerminateProgramForUnhandled.phpt
@@ -21,4 +21,4 @@ echo 'NEVER';
 
 ?>
 --EXPECTF--
-Fatal error: Unexpected RuntimeException: foo in %s line %d
+%AFatal error: Unexpected RuntimeException: foo in %s%s
diff --git a/tests/FunctionSetRejectionHandlerThatTriggersErrorHandlerThatThrowsShouldTerminateProgramForUnhandled.phpt b/tests/FunctionSetRejectionHandlerThatTriggersErrorHandlerThatThrowsShouldTerminateProgramForUnhandled.phpt
index 5ed9687..f5acd57 100644
--- a/tests/FunctionSetRejectionHandlerThatTriggersErrorHandlerThatThrowsShouldTerminateProgramForUnhandled.phpt
+++ b/tests/FunctionSetRejectionHandlerThatTriggersErrorHandlerThatThrowsShouldTerminateProgramForUnhandled.phpt
@@ -27,9 +27,4 @@ echo 'NEVER';
 --EXPECTF--
 Fatal error: Uncaught OverflowException from unhandled promise rejection handler: This function should never throw in %s:%d
 Stack trace:
-#0 [internal function]: {closure%S}(%S)
-#1 %s(%d): trigger_error(%S)
-#2 %s/src/Internal/RejectedPromise.php(%d): {closure%S}(%S)
-#3 %s/src/functions.php(%d): React\Promise\Internal\RejectedPromise->__destruct()
-#4 %s(%d): React\Promise\reject(%S)
-#5 %A{main}
+%A