diff --git a/src/Symfony/Component/EventDispatcher/Debug/TraceableEventDispatcher.php b/src/Symfony/Component/EventDispatcher/Debug/TraceableEventDispatcher.php
index 8f3b0bcd19..905169c3e0 100644
--- a/src/Symfony/Component/EventDispatcher/Debug/TraceableEventDispatcher.php
+++ b/src/Symfony/Component/EventDispatcher/Debug/TraceableEventDispatcher.php
@@ -53,7 +53,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
     /**
      * {@inheritdoc}
      */
-    public function addListener($eventName, $listener, $priority = 0)
+    public function addListener(string $eventName, $listener, int $priority = 0)
     {
         $this->dispatcher->addListener($eventName, $listener, $priority);
     }
@@ -69,7 +69,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
     /**
      * {@inheritdoc}
      */
-    public function removeListener($eventName, $listener)
+    public function removeListener(string $eventName, $listener)
     {
         if (isset($this->wrappedListeners[$eventName])) {
             foreach ($this->wrappedListeners[$eventName] as $index => $wrappedListener) {
@@ -95,7 +95,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
     /**
      * {@inheritdoc}
      */
-    public function getListeners($eventName = null)
+    public function getListeners(string $eventName = null)
     {
         return $this->dispatcher->getListeners($eventName);
     }
@@ -103,7 +103,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
     /**
      * {@inheritdoc}
      */
-    public function getListenerPriority($eventName, $listener)
+    public function getListenerPriority(string $eventName, $listener)
     {
         // we might have wrapped listeners for the event (if called while dispatching)
         // in that case get the priority by wrapper
@@ -121,7 +121,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
     /**
      * {@inheritdoc}
      */
-    public function hasListeners($eventName = null)
+    public function hasListeners(string $eventName = null)
     {
         return $this->dispatcher->hasListeners($eventName);
     }
@@ -272,7 +272,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
      *
      * @return mixed
      */
-    public function __call($method, $arguments)
+    public function __call(string $method, array $arguments)
     {
         return $this->dispatcher->{$method}(...$arguments);
     }
@@ -291,7 +291,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
     {
     }
 
-    private function preProcess($eventName)
+    private function preProcess(string $eventName): void
     {
         if (!$this->dispatcher->hasListeners($eventName)) {
             $this->orphanedEvents[$this->currentRequestHash][] = $eventName;
@@ -309,7 +309,7 @@ class TraceableEventDispatcher implements EventDispatcherInterface, ResetInterfa
         }
     }
 
-    private function postProcess($eventName)
+    private function postProcess(string $eventName): void
     {
         unset($this->wrappedListeners[$eventName]);
         $skipped = false;
diff --git a/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php b/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php
index 3e6493eb83..c5223ef94d 100644
--- a/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php
+++ b/src/Symfony/Component/EventDispatcher/DependencyInjection/RegisterListenersPass.php
@@ -134,7 +134,7 @@ class ExtractingEventDispatcher extends EventDispatcher implements EventSubscrib
     public static $aliases = [];
     public static $subscriber;
 
-    public function addListener($eventName, $listener, $priority = 0)
+    public function addListener(string $eventName, $listener, int $priority = 0)
     {
         $this->listeners[] = [$eventName, $listener[1], $priority];
     }
diff --git a/src/Symfony/Component/EventDispatcher/EventDispatcher.php b/src/Symfony/Component/EventDispatcher/EventDispatcher.php
index ecbb445874..88f0554774 100644
--- a/src/Symfony/Component/EventDispatcher/EventDispatcher.php
+++ b/src/Symfony/Component/EventDispatcher/EventDispatcher.php
@@ -70,7 +70,7 @@ class EventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function getListeners($eventName = null)
+    public function getListeners(string $eventName = null)
     {
         if (null !== $eventName) {
             if (empty($this->listeners[$eventName])) {
@@ -96,7 +96,7 @@ class EventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function getListenerPriority($eventName, $listener)
+    public function getListenerPriority(string $eventName, $listener)
     {
         if (empty($this->listeners[$eventName])) {
             return;
@@ -121,7 +121,7 @@ class EventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function hasListeners($eventName = null)
+    public function hasListeners(string $eventName = null)
     {
         if (null !== $eventName) {
             return !empty($this->listeners[$eventName]);
@@ -139,7 +139,7 @@ class EventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function addListener($eventName, $listener, $priority = 0)
+    public function addListener(string $eventName, $listener, int $priority = 0)
     {
         $this->listeners[$eventName][$priority][] = $listener;
         unset($this->sorted[$eventName], $this->optimized[$eventName]);
@@ -148,7 +148,7 @@ class EventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function removeListener($eventName, $listener)
+    public function removeListener(string $eventName, $listener)
     {
         if (empty($this->listeners[$eventName])) {
             return;
diff --git a/src/Symfony/Component/EventDispatcher/EventDispatcherInterface.php b/src/Symfony/Component/EventDispatcher/EventDispatcherInterface.php
index 146ae5b393..0620f74f19 100644
--- a/src/Symfony/Component/EventDispatcher/EventDispatcherInterface.php
+++ b/src/Symfony/Component/EventDispatcher/EventDispatcherInterface.php
@@ -30,12 +30,11 @@ interface EventDispatcherInterface extends ContractsEventDispatcherInterface
     /**
      * Adds an event listener that listens on the specified events.
      *
-     * @param string   $eventName The event to listen on
-     * @param callable $listener  The listener
-     * @param int      $priority  The higher this value, the earlier an event
-     *                            listener will be triggered in the chain (defaults to 0)
+     * @param callable $listener The listener
+     * @param int      $priority The higher this value, the earlier an event
+     *                           listener will be triggered in the chain (defaults to 0)
      */
-    public function addListener($eventName, $listener, $priority = 0);
+    public function addListener(string $eventName, $listener, int $priority = 0);
 
     /**
      * Adds an event subscriber.
@@ -48,40 +47,34 @@ interface EventDispatcherInterface extends ContractsEventDispatcherInterface
     /**
      * Removes an event listener from the specified events.
      *
-     * @param string   $eventName The event to remove a listener from
-     * @param callable $listener  The listener to remove
+     * @param callable $listener The listener to remove
      */
-    public function removeListener($eventName, $listener);
+    public function removeListener(string $eventName, $listener);
 
     public function removeSubscriber(EventSubscriberInterface $subscriber);
 
     /**
      * Gets the listeners of a specific event or all listeners sorted by descending priority.
      *
-     * @param string|null $eventName The name of the event
-     *
      * @return array The event listeners for the specified event, or all event listeners by event name
      */
-    public function getListeners($eventName = null);
+    public function getListeners(string $eventName = null);
 
     /**
      * Gets the listener priority for a specific event.
      *
      * Returns null if the event or the listener does not exist.
      *
-     * @param string   $eventName The name of the event
-     * @param callable $listener  The listener
+     * @param callable $listener The listener
      *
      * @return int|null The event listener priority
      */
-    public function getListenerPriority($eventName, $listener);
+    public function getListenerPriority(string $eventName, $listener);
 
     /**
      * Checks whether an event has any registered listeners.
      *
-     * @param string|null $eventName The name of the event
-     *
      * @return bool true if the specified event has any listeners, false otherwise
      */
-    public function hasListeners($eventName = null);
+    public function hasListeners(string $eventName = null);
 }
diff --git a/src/Symfony/Component/EventDispatcher/ImmutableEventDispatcher.php b/src/Symfony/Component/EventDispatcher/ImmutableEventDispatcher.php
index f164e8b298..8be7f4c530 100644
--- a/src/Symfony/Component/EventDispatcher/ImmutableEventDispatcher.php
+++ b/src/Symfony/Component/EventDispatcher/ImmutableEventDispatcher.php
@@ -36,7 +36,7 @@ class ImmutableEventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function addListener($eventName, $listener, $priority = 0)
+    public function addListener(string $eventName, $listener, int $priority = 0)
     {
         throw new \BadMethodCallException('Unmodifiable event dispatchers must not be modified.');
     }
@@ -52,7 +52,7 @@ class ImmutableEventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function removeListener($eventName, $listener)
+    public function removeListener(string $eventName, $listener)
     {
         throw new \BadMethodCallException('Unmodifiable event dispatchers must not be modified.');
     }
@@ -68,7 +68,7 @@ class ImmutableEventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function getListeners($eventName = null)
+    public function getListeners(string $eventName = null)
     {
         return $this->dispatcher->getListeners($eventName);
     }
@@ -76,7 +76,7 @@ class ImmutableEventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function getListenerPriority($eventName, $listener)
+    public function getListenerPriority(string $eventName, $listener)
     {
         return $this->dispatcher->getListenerPriority($eventName, $listener);
     }
@@ -84,7 +84,7 @@ class ImmutableEventDispatcher implements EventDispatcherInterface
     /**
      * {@inheritdoc}
      */
-    public function hasListeners($eventName = null)
+    public function hasListeners(string $eventName = null)
     {
         return $this->dispatcher->hasListeners($eventName);
     }