diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0755cde8..fa78b8cd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,10 +7,12 @@ on:
 jobs:
   PHPUnit:
     name: PHPUnit (PHP ${{ matrix.php }})
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     strategy:
       matrix:
         php:
+          - 8.5
+          - 8.4
           - 8.3
           - 8.2
           - 8.1
@@ -32,7 +34,7 @@ jobs:
           coverage: xdebug
           ini-file: development
           ini-values: disable_functions='' # do not disable PCNTL functions on PHP < 8.1
-          extensions: sockets, pcntl ${{ matrix.php >= 5.6 && ', event' || '' }} ${{ matrix.php >= 5.4 && ', ev' || '' }}
+          extensions: sockets, pcntl ${{ matrix.php >= 5.6 && ', event' || '' }} ${{ matrix.php >= 5.4 && (matrix.php < 8.0 && ', ev-1.1.5' || ', ev') || '' }}
         env:
           fail-fast: true # fail step if any extension can not be installed
       - run: composer install
@@ -43,11 +45,13 @@ jobs:
 
   PHPUnit-Unstable:
     name: PHPUnit (Unstable PHP ${{ matrix.php }})
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     continue-on-error: true
     strategy:
       matrix:
         php:
+          - 8.5
+          - 8.4
           - 8.3
           - 8.2
           - 8.1
@@ -77,8 +81,8 @@ jobs:
         if: ${{ matrix.php >= 7.0 }}
       - name: Install legacy ext-libevent on PHP < 7.0
         run: |
-          sudo apt-get update && sudo apt-get install libevent-dev
-          curl http://pecl.php.net/get/libevent-0.1.0.tgz | tar -xz
+          sudo apt-get update && sudo apt --fix-broken install && sudo apt-get install libevent-dev
+          curl https://pecl.php.net/get/libevent-0.1.0.tgz | tar -xz
           pushd libevent-0.1.0
           phpize
           ./configure
@@ -111,6 +115,8 @@ jobs:
     strategy:
       matrix:
         php:
+          - 8.5
+          - 8.4
           - 8.3
           - 8.2
           - 8.1
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e634b12e..7d419095 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## 1.6.0 (2025-11-17)
+
+*   Feature: Improve PHP 8.5+ support by avoiding deprecated method calls.
+    (#280 and #282 by @WyriHaximus)
+
 ## 1.5.0 (2023-11-13)
 
 *   Feature: Improve performance by using `spl_object_id()` on PHP 7.2+.
diff --git a/README.md b/README.md
index 88a3e18b..bbdf1cff 100644
--- a/README.md
+++ b/README.md
@@ -889,7 +889,7 @@ This project follows [SemVer](https://semver.org/).
 This will install the latest supported version:
 
 ```bash
-composer require react/event-loop:^1.5
+composer require react/event-loop:^1.6
 ```
 
 See also the [CHANGELOG](CHANGELOG.md) for details about version upgrades.
diff --git a/src/ExtEvLoop.php b/src/ExtEvLoop.php
index a3fcec68..7689ff57 100644
--- a/src/ExtEvLoop.php
+++ b/src/ExtEvLoop.php
@@ -143,13 +143,13 @@ public function addTimer($interval, $callback)
         $callback = function () use ($timer, $timers, $that) {
             \call_user_func($timer->getCallback(), $timer);
 
-            if ($timers->contains($timer)) {
+            if ($timers->offsetExists($timer)) {
                 $that->cancelTimer($timer);
             }
         };
 
         $event = $this->loop->timer($timer->getInterval(), 0.0, $callback);
-        $this->timers->attach($timer, $event);
+        $this->timers->offsetSet($timer, $event);
 
         return $timer;
     }
@@ -163,7 +163,7 @@ public function addPeriodicTimer($interval, $callback)
         };
 
         $event = $this->loop->timer($timer->getInterval(), $timer->getInterval(), $callback);
-        $this->timers->attach($timer, $event);
+        $this->timers->offsetSet($timer, $event);
 
         return $timer;
     }
@@ -176,7 +176,7 @@ public function cancelTimer(TimerInterface $timer)
 
         $event = $this->timers[$timer];
         $event->stop();
-        $this->timers->detach($timer);
+        $this->timers->offsetUnset($timer);
     }
 
     public function futureTick($listener)
diff --git a/src/ExtEventLoop.php b/src/ExtEventLoop.php
index b162a402..2f26d746 100644
--- a/src/ExtEventLoop.php
+++ b/src/ExtEventLoop.php
@@ -64,7 +64,7 @@ public function __destruct()
     {
         // explicitly clear all references to Event objects to prevent SEGFAULTs on Windows
         foreach ($this->timerEvents as $timer) {
-            $this->timerEvents->detach($timer);
+            $this->timerEvents->offsetUnset($timer);
         }
 
         $this->readEvents = array();
@@ -157,9 +157,9 @@ public function addPeriodicTimer($interval, $callback)
 
     public function cancelTimer(TimerInterface $timer)
     {
-        if ($this->timerEvents->contains($timer)) {
+        if ($this->timerEvents->offsetExists($timer)) {
             $this->timerEvents[$timer]->free();
-            $this->timerEvents->detach($timer);
+            $this->timerEvents->offsetUnset($timer);
         }
     }
 
@@ -243,7 +243,7 @@ private function createTimerCallback()
         $this->timerCallback = function ($_, $__, $timer) use ($timers) {
             \call_user_func($timer->getCallback(), $timer);
 
-            if (!$timer->isPeriodic() && $timers->contains($timer)) {
+            if (!$timer->isPeriodic() && $timers->offsetExists($timer)) {
                 $this->cancelTimer($timer);
             }
         };
diff --git a/src/ExtUvLoop.php b/src/ExtUvLoop.php
index 4434720d..29aa86b4 100644
--- a/src/ExtUvLoop.php
+++ b/src/ExtUvLoop.php
@@ -119,13 +119,13 @@ public function addTimer($interval, $callback)
         $callback = function () use ($timer, $timers, $that) {
             \call_user_func($timer->getCallback(), $timer);
 
-            if ($timers->contains($timer)) {
+            if ($timers->offsetExists($timer)) {
                 $that->cancelTimer($timer);
             }
         };
 
         $event = \uv_timer_init($this->uv);
-        $this->timers->attach($timer, $event);
+        $this->timers->offsetSet($timer, $event);
         \uv_timer_start(
             $event,
             $this->convertFloatSecondsToMilliseconds($interval),
@@ -149,7 +149,7 @@ public function addPeriodicTimer($interval, $callback)
 
         $interval = $this->convertFloatSecondsToMilliseconds($interval);
         $event = \uv_timer_init($this->uv);
-        $this->timers->attach($timer, $event);
+        $this->timers->offsetSet($timer, $event);
         \uv_timer_start(
             $event,
             $interval,
@@ -167,7 +167,7 @@ public function cancelTimer(TimerInterface $timer)
     {
         if (isset($this->timers[$timer])) {
             @\uv_timer_stop($this->timers[$timer]);
-            $this->timers->detach($timer);
+            $this->timers->offsetUnset($timer);
         }
     }
 
@@ -329,9 +329,17 @@ private function convertFloatSecondsToMilliseconds($interval)
         }
 
         $maxValue = (int) (\PHP_INT_MAX / 1000);
-        $intInterval = (int) $interval;
+        $intervalOverflow = false;
+        if (PHP_VERSION_ID > 80499 && $interval >= \PHP_INT_MAX + 1) {
+            $intervalOverflow = true;
+        } else {
+            $intInterval = (int) $interval;
+            if (($intInterval <= 0 && $interval > 1) || $intInterval >= $maxValue) {
+                $intervalOverflow = true;
+            }
+        }
 
-        if (($intInterval <= 0 && $interval > 1) || $intInterval >= $maxValue) {
+        if ($intervalOverflow) {
             throw new \InvalidArgumentException(
                 "Interval overflow, value must be lower than '{$maxValue}', but '{$interval}' passed."
             );
diff --git a/tests/LoopTest.php b/tests/LoopTest.php
index 42f85244..25b6e855 100644
--- a/tests/LoopTest.php
+++ b/tests/LoopTest.php
@@ -64,7 +64,9 @@ public function testStaticAddReadStreamCallsAddReadStreamOnLoopInstance()
     public function testStaticAddReadStreamWithNoDefaultLoopCallsAddReadStreamOnNewLoopInstance()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $stream = stream_socket_server('127.0.0.1:0');
@@ -90,7 +92,9 @@ public function testStaticAddWriteStreamCallsAddWriteStreamOnLoopInstance()
     public function testStaticAddWriteStreamWithNoDefaultLoopCallsAddWriteStreamOnNewLoopInstance()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $stream = stream_socket_server('127.0.0.1:0');
@@ -115,7 +119,9 @@ public function testStaticRemoveReadStreamCallsRemoveReadStreamOnLoopInstance()
     public function testStaticRemoveReadStreamWithNoDefaultLoopIsNoOp()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $stream = tmpfile();
@@ -139,7 +145,9 @@ public function testStaticRemoveWriteStreamCallsRemoveWriteStreamOnLoopInstance(
     public function testStaticRemoveWriteStreamWithNoDefaultLoopIsNoOp()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $stream = tmpfile();
@@ -167,7 +175,9 @@ public function testStaticAddTimerCallsAddTimerOnLoopInstanceAndReturnsTimerInst
     public function testStaticAddTimerWithNoDefaultLoopCallsAddTimerOnNewLoopInstance()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $interval = 1.0;
@@ -197,7 +207,9 @@ public function testStaticAddPeriodicTimerCallsAddPeriodicTimerOnLoopInstanceAnd
     public function testStaticAddPeriodicTimerWithNoDefaultLoopCallsAddPeriodicTimerOnNewLoopInstance()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $interval = 1.0;
@@ -224,7 +236,9 @@ public function testStaticCancelTimerCallsCancelTimerOnLoopInstance()
     public function testStaticCancelTimerWithNoDefaultLoopIsNoOp()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $timer = $this->getMockBuilder('React\EventLoop\TimerInterface')->getMock();
@@ -248,7 +262,9 @@ public function testStaticFutureTickCallsFutureTickOnLoopInstance()
     public function testStaticFutureTickWithNoDefaultLoopCallsFutureTickOnNewLoopInstance()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $listener = function () { };
@@ -277,7 +293,9 @@ public function testStaticAddSignalWithNoDefaultLoopCallsAddSignalOnNewLoopInsta
         }
 
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $signal = 1;
@@ -307,7 +325,9 @@ public function testStaticRemoveSignalCallsRemoveSignalOnLoopInstance()
     public function testStaticRemoveSignalWithNoDefaultLoopIsNoOp()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         $signal = 1;
@@ -330,7 +350,9 @@ public function testStaticRunCallsRunOnLoopInstance()
     public function testStaticRunWithNoDefaultLoopCallsRunsOnNewLoopInstance()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         Loop::run();
@@ -351,7 +373,9 @@ public function testStaticStopCallsStopOnLoopInstance()
     public function testStaticStopCallWithNoDefaultLoopIsNoOp()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
 
         Loop::stop();
@@ -366,7 +390,9 @@ public function testStaticStopCallWithNoDefaultLoopIsNoOp()
     public function unsetLoopFromLoopAccessor()
     {
         $ref = new \ReflectionProperty('React\EventLoop\Loop', 'instance');
-        $ref->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $ref->setAccessible(true);
+        }
         $ref->setValue(null, null);
     }
 }