diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index 8f1baee..888d387 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        php: ['8.2']
+        php: ['8.3']
         setup: ['stable']
 
     steps:
diff --git a/.github/workflows/multi-tester.yml b/.github/workflows/multi-tester.yml
index 98d9ae7..d3e2cd0 100644
--- a/.github/workflows/multi-tester.yml
+++ b/.github/workflows/multi-tester.yml
@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        php: ['8.2']
+        php: ['8.3']
         setup: ['stable']
 
     name: PHP ${{ matrix.php }} - ${{ matrix.setup || 'stable' }}
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 6ddb7ee..694a0a5 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['8.2', '8.3']
+        php: ['8.2', '8.3', '8.4']
         setup: ['lowest', 'stable']
 
     name: PHP ${{ matrix.php }} - ${{ matrix.setup || 'stable' }}
diff --git a/src/PreciseTime.php b/src/PreciseTime.php
index 342ce7f..f155b88 100644
--- a/src/PreciseTime.php
+++ b/src/PreciseTime.php
@@ -17,7 +17,7 @@ protected function __construct(
         parent::__construct(0, 0, $data);
     }
 
-    public static function fromString(string $string, mixed $data = null, ?DateTimeInterface $date = null): parent
+    public static function fromString(string $string, mixed $data = null, ?DateTimeInterface $date = null): self
     {
         if ($date !== null) {
             throw new InvalidArgumentException(static::class.' does not support date reference point');
@@ -36,7 +36,7 @@ public function minutes(): int
         return (int) $this->dateTime->format('i');
     }
 
-    public static function fromDateTime(DateTimeInterface $dateTime, mixed $data = null): parent
+    public static function fromDateTime(DateTimeInterface $dateTime, mixed $data = null): self
     {
         return new self($dateTime, $data);
     }
diff --git a/tests/OpeningHoursTest.php b/tests/OpeningHoursTest.php
index 411a578..3aa696c 100644
--- a/tests/OpeningHoursTest.php
+++ b/tests/OpeningHoursTest.php
@@ -928,7 +928,7 @@ public function it_can_handle_timezone_for_date_string($timezone)
         $this->assertTrue($openingHours->isOpenOn('2020-10-19'));
     }
 
-    public function timezones()
+    public static function timezones(): array
     {
         return [
             ['-12:00'],