diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 5bc6f11c0..7a82ca251 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -28,6 +28,7 @@ jobs:
           - '8.1'
           - '8.2'
           - '8.3'
+          - '8.4'
         redis:
           - 3
           - 4
@@ -69,7 +70,7 @@ jobs:
         run: vendor/bin/phpunit --coverage-clover build/logs/clover-default.xml --coverage-filter ./src
 
       - name: Run tests using Relay
-        if: ${{ matrix.redis >= '6' }}
+        if: ${{ matrix.php != '8.4' && matrix.redis >= '6' }}
         run: vendor/bin/phpunit -c phpunit.relay.xml
 
       - name: Run tests using Relay with coverage
diff --git a/src/Client.php b/src/Client.php
index c73ff2e51..7c0b4add3 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -472,7 +472,7 @@ public function pipeline(...$arguments)
      *
      * @return Pipeline|array
      */
-    protected function createPipeline(array $options = null, $callable = null)
+    protected function createPipeline(?array $options = null, $callable = null)
     {
         if (isset($options['atomic']) && $options['atomic']) {
             $class = Atomic::class;
@@ -520,12 +520,12 @@ public function transaction(...$arguments)
     /**
      * Actual transaction context initializer method.
      *
-     * @param array $options  Options for the context.
-     * @param mixed $callable Optional callable used to execute the context.
+     * @param array|null $options  Options for the context.
+     * @param mixed      $callable Optional callable used to execute the context.
      *
      * @return MultiExecTransaction|array
      */
-    protected function createTransaction(array $options = null, $callable = null)
+    protected function createTransaction(?array $options = null, $callable = null)
     {
         $transaction = new MultiExecTransaction($this, $options);
 
@@ -552,12 +552,12 @@ public function pubSubLoop(...$arguments)
     /**
      * Actual publish/subscribe context initializer method.
      *
-     * @param array $options  Options for the context.
-     * @param mixed $callable Optional callable used to execute the context.
+     * @param array|null $options  Options for the context.
+     * @param mixed      $callable Optional callable used to execute the context.
      *
      * @return PubSubConsumer|null
      */
-    protected function createPubSub(array $options = null, $callable = null)
+    protected function createPubSub(?array $options = null, $callable = null)
     {
         if ($this->connection instanceof RelayConnection) {
             $pubsub = new RelayPubSubConsumer($this, $options);
diff --git a/src/ClientContextInterface.php b/src/ClientContextInterface.php
index e443ee5d1..d6cb74512 100644
--- a/src/ClientContextInterface.php
+++ b/src/ClientContextInterface.php
@@ -65,8 +65,8 @@
  * @method $this randomkey()
  * @method $this rename($key, $target)
  * @method $this renamenx($key, $target)
- * @method $this scan($cursor, array $options = null)
- * @method $this sort($key, array $options = null)
+ * @method $this scan($cursor, ?array $options = null)
+ * @method $this sort($key, ?array $options = null)
  * @method $this sort_ro(string $key, ?string $byPattern = null, ?LimitOffsetCount $limit = null, array $getPatterns = [], ?string $sorting = null, bool $alpha = false)
  * @method $this ttl($key)
  * @method $this type($key)
@@ -163,7 +163,7 @@
  * @method $this hmget($key, array $fields)
  * @method $this hmset($key, array $dictionary)
  * @method $this hrandfield(string $key, int $count = 1, bool $withValues = false)
- * @method $this hscan($key, $cursor, array $options = null)
+ * @method $this hscan($key, $cursor, ?array $options = null)
  * @method $this hset($key, $field, $value)
  * @method $this hsetnx($key, $field, $value)
  * @method $this hvals($key)
@@ -225,7 +225,7 @@
  * @method $this spop($key, $count = null)
  * @method $this srandmember($key, $count = null)
  * @method $this srem($key, $member)
- * @method $this sscan($key, $cursor, array $options = null)
+ * @method $this sscan($key, $cursor, ?array $options = null)
  * @method $this sunion(array|string $keys)
  * @method $this sunionstore($destination, array|string $keys)
  * @method $this tdigestadd(string $key, float ...$value)
@@ -255,7 +255,7 @@
  * @method $this tsdecrby(string $key, float $value, ?DecrByArguments $arguments = null)
  * @method $this tsdel(string $key, int $fromTimestamp, int $toTimestamp)
  * @method $this tsdeleterule(string $sourceKey, string $destKey)
- * @method $this tsget(string $key, GetArguments $arguments = null)
+ * @method $this tsget(string $key, ?GetArguments $arguments = null)
  * @method $this tsincrby(string $key, float $value, ?IncrByArguments $arguments = null)
  * @method $this tsinfo(string $key, ?InfoArguments $arguments = null)
  * @method $this tsmadd(mixed ...$keyTimestampValue)
@@ -277,22 +277,22 @@
  * @method $this zmpop(array $keys, string $modifier = 'min', int $count = 1)
  * @method $this zmscore(string $key, string ...$member)
  * @method $this zrandmember(string $key, int $count = 1, bool $withScores = false)
- * @method $this zrange($key, $start, $stop, array $options = null)
- * @method $this zrangebyscore($key, $min, $max, array $options = null)
+ * @method $this zrange($key, $start, $stop, ?array $options = null)
+ * @method $this zrangebyscore($key, $min, $max, ?array $options = null)
  * @method $this zrangestore(string $destination, string $source, int|string $min, string|int $max, string|bool $by = false, bool $reversed = false, bool $limit = false, int $offset = 0, int $count = 0)
  * @method $this zrank($key, $member)
  * @method $this zrem($key, $member)
  * @method $this zremrangebyrank($key, $start, $stop)
  * @method $this zremrangebyscore($key, $min, $max)
- * @method $this zrevrange($key, $start, $stop, array $options = null)
- * @method $this zrevrangebyscore($key, $max, $min, array $options = null)
+ * @method $this zrevrange($key, $start, $stop, ?array $options = null)
+ * @method $this zrevrangebyscore($key, $max, $min, ?array $options = null)
  * @method $this zrevrank($key, $member)
  * @method $this zunion(array $keys, int[] $weights = [], string $aggregate = 'sum', bool $withScores = false)
  * @method $this zunionstore(string $destination, array $keys, int[] $weights = [], string $aggregate = 'sum')
  * @method $this zscore($key, $member)
- * @method $this zscan($key, $cursor, array $options = null)
- * @method $this zrangebylex($key, $start, $stop, array $options = null)
- * @method $this zrevrangebylex($key, $start, $stop, array $options = null)
+ * @method $this zscan($key, $cursor, ?array $options = null)
+ * @method $this zrangebylex($key, $start, $stop, ?array $options = null)
+ * @method $this zrevrangebylex($key, $start, $stop, ?array $options = null)
  * @method $this zremrangebylex($key, $min, $max)
  * @method $this zlexcount($key, $min, $max)
  * @method $this pexpiretime(string $key)
@@ -312,7 +312,7 @@
  * @method $this evalsha($script, $numkeys, $keyOrArg1 = null, $keyOrArgN = null)
  * @method $this evalsha_ro(string $sha1, array $keys, ...$argument)
  * @method $this script($subcommand, $argument = null)
- * @method $this shutdown(bool $noSave = null, bool $now = false, bool $force = false, bool $abort = false)
+ * @method $this shutdown(?bool $noSave = null, bool $now = false, bool $force = false, bool $abort = false)
  * @method $this auth($password)
  * @method $this echo($message)
  * @method $this ping($message = null)
@@ -335,8 +335,8 @@
  * @method $this geohash($key, array $members)
  * @method $this geopos($key, array $members)
  * @method $this geodist($key, $member1, $member2, $unit = null)
- * @method $this georadius($key, $longitude, $latitude, $radius, $unit, array $options = null)
- * @method $this georadiusbymember($key, $member, $radius, $unit, array $options = null)
+ * @method $this georadius($key, $longitude, $latitude, $radius, $unit, ?array $options = null)
+ * @method $this georadiusbymember($key, $member, $radius, $unit, ?array $options = null)
  * @method $this geosearch(string $key, FromInterface $from, ByInterface $by, ?string $sorting = null, int $count = -1, bool $any = false, bool $withCoord = false, bool $withDist = false, bool $withHash = false)
  * @method $this geosearchstore(string $destination, string $source, FromInterface $from, ByInterface $by, ?string $sorting = null, int $count = -1, bool $any = false, bool $storeDist = false)
  *
diff --git a/src/ClientInterface.php b/src/ClientInterface.php
index 5250dabd5..e27c43f18 100644
--- a/src/ClientInterface.php
+++ b/src/ClientInterface.php
@@ -74,8 +74,8 @@
  * @method string|null       randomkey()
  * @method mixed             rename(string $key, string $target)
  * @method int               renamenx(string $key, string $target)
- * @method array             scan($cursor, array $options = null)
- * @method array             sort(string $key, array $options = null)
+ * @method array             scan($cursor, ?array $options = null)
+ * @method array             sort(string $key, ?array $options = null)
  * @method array             sort_ro(string $key, ?string $byPattern = null, ?LimitOffsetCount $limit = null, array $getPatterns = [], ?string $sorting = null, bool $alpha = false)
  * @method int               ttl(string $key)
  * @method mixed             type(string $key)
@@ -172,7 +172,7 @@
  * @method array             hmget(string $key, array $fields)
  * @method mixed             hmset(string $key, array $dictionary)
  * @method array             hrandfield(string $key, int $count = 1, bool $withValues = false)
- * @method array             hscan(string $key, $cursor, array $options = null)
+ * @method array             hscan(string $key, $cursor, ?array $options = null)
  * @method int               hset(string $key, string $field, string $value)
  * @method int               hsetnx(string $key, string $field, string $value)
  * @method array             hvals(string $key)
@@ -231,10 +231,10 @@
  * @method string[]          smembers(string $key)
  * @method array             smismember(string $key, string ...$members)
  * @method int               smove(string $source, string $destination, string $member)
- * @method string|array|null spop(string $key, int $count = null)
- * @method string|null       srandmember(string $key, int $count = null)
+ * @method string|array|null spop(string $key, ?int $count = null)
+ * @method string|null       srandmember(string $key, ?int $count = null)
  * @method int               srem(string $key, array|string $member)
- * @method array             sscan(string $key, int $cursor, array $options = null)
+ * @method array             sscan(string $key, int $cursor, ?array $options = null)
  * @method string[]          sunion(array|string $keys)
  * @method int               sunionstore(string $destination, array|string $keys)
  * @method int               touch(string[]|string $keyOrKeys, string ...$keys = null)
@@ -265,7 +265,7 @@
  * @method int               tsdecrby(string $key, float $value, ?DecrByArguments $arguments = null)
  * @method int               tsdel(string $key, int $fromTimestamp, int $toTimestamp)
  * @method Status            tsdeleterule(string $sourceKey, string $destKey)
- * @method array             tsget(string $key, GetArguments $arguments = null)
+ * @method array             tsget(string $key, ?GetArguments $arguments = null)
  * @method int               tsincrby(string $key, float $value, ?IncrByArguments $arguments = null)
  * @method array             tsinfo(string $key, ?InfoArguments $arguments = null)
  * @method array             tsmadd(mixed ...$keyTimestampValue)
@@ -275,12 +275,12 @@
  * @method array             tsqueryindex(string ...$filterExpression)
  * @method array             tsrange(string $key, $fromTimestamp, $toTimestamp, ?RangeArguments $arguments = null)
  * @method array             tsrevrange(string $key, $fromTimestamp, $toTimestamp, ?RangeArguments $arguments = null)
- * @method string            xadd(string $key, array $dictionary, string $id = '*', array $options = null)
+ * @method string            xadd(string $key, array $dictionary, string $id = '*', ?array $options = null)
  * @method int               xdel(string $key, string ...$id)
  * @method int               xlen(string $key)
  * @method array             xrevrange(string $key, string $end, string $start, ?int $count = null)
  * @method array             xrange(string $key, string $start, string $end, ?int $count = null)
- * @method string            xtrim(string $key, array|string $strategy, string $threshold, array $options = null)
+ * @method string            xtrim(string $key, array|string $strategy, string $threshold, ?array $options = null)
  * @method int               zadd(string $key, array $membersAndScoresDictionary)
  * @method int               zcard(string $key)
  * @method string            zcount(string $key, int|string $min, int|string $max)
@@ -295,22 +295,22 @@
  * @method array             zpopmin(string $key, int $count = 1)
  * @method array             zpopmax(string $key, int $count = 1)
  * @method mixed             zrandmember(string $key, int $count = 1, bool $withScores = false)
- * @method array             zrange(string $key, int|string $start, int|string $stop, array $options = null)
- * @method array             zrangebyscore(string $key, int|string $min, int|string $max, array $options = null)
+ * @method array             zrange(string $key, int|string $start, int|string $stop, ?array $options = null)
+ * @method array             zrangebyscore(string $key, int|string $min, int|string $max, ?array $options = null)
  * @method int               zrangestore(string $destination, string $source, int|string $min, int|string $max, string|bool $by = false, bool $reversed = false, bool $limit = false, int $offset = 0, int $count = 0)
  * @method int|null          zrank(string $key, string $member)
  * @method int               zrem(string $key, string ...$member)
  * @method int               zremrangebyrank(string $key, int|string $start, int|string $stop)
  * @method int               zremrangebyscore(string $key, int|string $min, int|string $max)
- * @method array             zrevrange(string $key, int|string $start, int|string $stop, array $options = null)
- * @method array             zrevrangebyscore(string $key, int|string $max, int|string $min, array $options = null)
+ * @method array             zrevrange(string $key, int|string $start, int|string $stop, ?array $options = null)
+ * @method array             zrevrangebyscore(string $key, int|string $max, int|string $min, ?array $options = null)
  * @method int|null          zrevrank(string $key, string $member)
  * @method array             zunion(array $keys, int[] $weights = [], string $aggregate = 'sum', bool $withScores = false)
  * @method int               zunionstore(string $destination, array $keys, int[] $weights = [], string $aggregate = 'sum')
  * @method string|null       zscore(string $key, string $member)
- * @method array             zscan(string $key, int $cursor, array $options = null)
- * @method array             zrangebylex(string $key, string $start, string $stop, array $options = null)
- * @method array             zrevrangebylex(string $key, string $start, string $stop, array $options = null)
+ * @method array             zscan(string $key, int $cursor, ?array $options = null)
+ * @method array             zrangebylex(string $key, string $start, string $stop, ?array $options = null)
+ * @method array             zrevrangebylex(string $key, string $start, string $stop, ?array $options = null)
  * @method int               zremrangebylex(string $key, string $min, string $max)
  * @method int               zlexcount(string $key, string $min, string $max)
  * @method int               pexpiretime(string $key)
@@ -330,10 +330,10 @@
  * @method mixed             evalsha(string $script, int $numkeys, string ...$keyOrArg = null)
  * @method mixed             evalsha_ro(string $sha1, array $keys, ...$argument)
  * @method mixed             script($subcommand, $argument = null)
- * @method Status            shutdown(bool $noSave = null, bool $now = false, bool $force = false, bool $abort = false)
+ * @method Status            shutdown(?bool $noSave = null, bool $now = false, bool $force = false, bool $abort = false)
  * @method mixed             auth(string $password)
  * @method string            echo(string $message)
- * @method mixed             ping(string $message = null)
+ * @method mixed             ping(?string $message = null)
  * @method mixed             select(int $database)
  * @method mixed             bgrewriteaof()
  * @method mixed             bgsave()
@@ -353,8 +353,8 @@
  * @method array             geohash(string $key, array $members)
  * @method array             geopos(string $key, array $members)
  * @method string|null       geodist(string $key, $member1, $member2, $unit = null)
- * @method array             georadius(string $key, $longitude, $latitude, $radius, $unit, array $options = null)
- * @method array             georadiusbymember(string $key, $member, $radius, $unit, array $options = null)
+ * @method array             georadius(string $key, $longitude, $latitude, $radius, $unit, ?array $options = null)
+ * @method array             georadiusbymember(string $key, $member, $radius, $unit, ?array $options = null)
  * @method array             geosearch(string $key, FromInterface $from, ByInterface $by, ?string $sorting = null, int $count = -1, bool $any = false, bool $withCoord = false, bool $withDist = false, bool $withHash = false)
  * @method int               geosearchstore(string $destination, string $source, FromInterface $from, ByInterface $by, ?string $sorting = null, int $count = -1, bool $any = false, bool $storeDist = false)
  *
diff --git a/src/Cluster/PredisStrategy.php b/src/Cluster/PredisStrategy.php
index 574b86f9e..084c52585 100644
--- a/src/Cluster/PredisStrategy.php
+++ b/src/Cluster/PredisStrategy.php
@@ -23,9 +23,9 @@ class PredisStrategy extends ClusterStrategy
     protected $distributor;
 
     /**
-     * @param DistributorInterface $distributor Optional distributor instance.
+     * @param DistributorInterface|null $distributor Optional distributor instance.
      */
-    public function __construct(DistributorInterface $distributor = null)
+    public function __construct(?DistributorInterface $distributor = null)
     {
         parent::__construct();
 
diff --git a/src/Cluster/RedisStrategy.php b/src/Cluster/RedisStrategy.php
index 8ae5c0f5e..cf1fbafed 100644
--- a/src/Cluster/RedisStrategy.php
+++ b/src/Cluster/RedisStrategy.php
@@ -25,9 +25,9 @@ class RedisStrategy extends ClusterStrategy
     protected $hashGenerator;
 
     /**
-     * @param HashGeneratorInterface $hashGenerator Hash generator instance.
+     * @param HashGeneratorInterface|null $hashGenerator Hash generator instance.
      */
-    public function __construct(HashGeneratorInterface $hashGenerator = null)
+    public function __construct(?HashGeneratorInterface $hashGenerator = null)
     {
         parent::__construct();
 
diff --git a/src/Command/Redis/Container/FunctionContainer.php b/src/Command/Redis/Container/FunctionContainer.php
index 8f2a673d1..dfa309eea 100644
--- a/src/Command/Redis/Container/FunctionContainer.php
+++ b/src/Command/Redis/Container/FunctionContainer.php
@@ -19,9 +19,9 @@
  * @method string dump()
  * @method Status flush(?string $mode = null)
  * @method Status kill()
- * @method array  list(string $libraryNamePattern = null, bool $withCode = false)
+ * @method array  list(?string $libraryNamePattern = null, bool $withCode = false)
  * @method string load(string $functionCode, bool $replace = 'false')
- * @method Status restore(string $value, string $policy = null)
+ * @method Status restore(string $value, ?string $policy = null)
  * @method array  stats()
  */
 class FunctionContainer extends AbstractContainer
diff --git a/src/Command/Strategy/SubcommandStrategyResolver.php b/src/Command/Strategy/SubcommandStrategyResolver.php
index cda84268e..b714d5276 100644
--- a/src/Command/Strategy/SubcommandStrategyResolver.php
+++ b/src/Command/Strategy/SubcommandStrategyResolver.php
@@ -23,7 +23,7 @@ class SubcommandStrategyResolver implements StrategyResolverInterface
      */
     private $separator;
 
-    public function __construct(string $separator = null)
+    public function __construct(?string $separator = null)
     {
         $this->separator = $separator;
     }
diff --git a/src/CommunicationException.php b/src/CommunicationException.php
index 0fc7c07a6..9fd69a021 100644
--- a/src/CommunicationException.php
+++ b/src/CommunicationException.php
@@ -32,7 +32,7 @@ public function __construct(
         NodeConnectionInterface $connection,
         $message = '',
         $code = 0,
-        Exception $innerException = null
+        ?Exception $innerException = null
     ) {
         parent::__construct(
             is_null($message) ? '' : $message,
diff --git a/src/Configuration/Options.php b/src/Configuration/Options.php
index 3fff04129..7ff7f26e3 100644
--- a/src/Configuration/Options.php
+++ b/src/Configuration/Options.php
@@ -41,9 +41,9 @@ class Options implements OptionsInterface
     protected $input;
 
     /**
-     * @param array $options Named array of client options
+     * @param array|null $options Named array of client options
      */
-    public function __construct(array $options = null)
+    public function __construct(?array $options = null)
     {
         $this->input = $options ?? [];
     }
diff --git a/src/Connection/Cluster/PredisCluster.php b/src/Connection/Cluster/PredisCluster.php
index c30fd09d3..7d5658611 100644
--- a/src/Connection/Cluster/PredisCluster.php
+++ b/src/Connection/Cluster/PredisCluster.php
@@ -50,9 +50,9 @@ class PredisCluster implements ClusterInterface, IteratorAggregate, Countable
     private $distributor;
 
     /**
-     * @param StrategyInterface $strategy Optional cluster strategy.
+     * @param StrategyInterface|null $strategy Optional cluster strategy.
      */
-    public function __construct(StrategyInterface $strategy = null)
+    public function __construct(?StrategyInterface $strategy = null)
     {
         $this->strategy = $strategy ?: new PredisStrategy();
         $this->distributor = $this->strategy->getDistributor();
diff --git a/src/Connection/Cluster/RedisCluster.php b/src/Connection/Cluster/RedisCluster.php
index 0287de2ac..b44360bb9 100644
--- a/src/Connection/Cluster/RedisCluster.php
+++ b/src/Connection/Cluster/RedisCluster.php
@@ -65,12 +65,12 @@ class RedisCluster implements ClusterInterface, IteratorAggregate, Countable
     private $retryInterval = 10;
 
     /**
-     * @param FactoryInterface  $connections Optional connection factory.
-     * @param StrategyInterface $strategy    Optional cluster strategy.
+     * @param FactoryInterface       $connections Optional connection factory.
+     * @param StrategyInterface|null $strategy    Optional cluster strategy.
      */
     public function __construct(
         FactoryInterface $connections,
-        StrategyInterface $strategy = null
+        ?StrategyInterface $strategy = null
     ) {
         $this->connections = $connections;
         $this->strategy = $strategy ?: new RedisClusterStrategy();
@@ -271,9 +271,9 @@ private function queryClusterNodeForSlotMap(NodeConnectionInterface $connection)
      * the CLUSTER SLOTS command against the specified node or a random one from
      * the pool.
      *
-     * @param NodeConnectionInterface $connection Optional connection instance.
+     * @param NodeConnectionInterface|null $connection Optional connection instance.
      */
-    public function askSlotMap(NodeConnectionInterface $connection = null)
+    public function askSlotMap(?NodeConnectionInterface $connection = null)
     {
         if (!$connection && !$connection = $this->getRandomConnection()) {
             return;
diff --git a/src/Connection/CompositeStreamConnection.php b/src/Connection/CompositeStreamConnection.php
index ad69cbc12..db1ba9418 100644
--- a/src/Connection/CompositeStreamConnection.php
+++ b/src/Connection/CompositeStreamConnection.php
@@ -26,12 +26,12 @@ class CompositeStreamConnection extends StreamConnection implements CompositeCon
     protected $protocol;
 
     /**
-     * @param ParametersInterface        $parameters Initialization parameters for the connection.
-     * @param ProtocolProcessorInterface $protocol   Protocol processor.
+     * @param ParametersInterface             $parameters Initialization parameters for the connection.
+     * @param ProtocolProcessorInterface|null $protocol   Protocol processor.
      */
     public function __construct(
         ParametersInterface $parameters,
-        ProtocolProcessorInterface $protocol = null
+        ?ProtocolProcessorInterface $protocol = null
     ) {
         $this->parameters = $this->assertParameters($parameters);
         $this->protocol = $protocol ?: new TextProtocolProcessor();
diff --git a/src/Connection/RelayMethods.php b/src/Connection/RelayMethods.php
index a52c4a035..07e7c13ad 100644
--- a/src/Connection/RelayMethods.php
+++ b/src/Connection/RelayMethods.php
@@ -28,11 +28,11 @@ public function onFlushed(?callable $callback)
     /**
      * Registers a new `invalidated` event listener.
      *
-     * @param  callable $callback
-     * @param  string   $pattern
+     * @param  callable    $callback
+     * @param  string|null $pattern
      * @return bool
      */
-    public function onInvalidated(?callable $callback, string $pattern = null)
+    public function onInvalidated(?callable $callback, ?string $pattern = null)
     {
         return $this->client->onInvalidated($callback, $pattern);
     }
@@ -129,7 +129,7 @@ public function maxMemory()
      * @param  ?int    $db
      * @return bool
      */
-    public function flushMemory(string $endpointId = null, int $db = null)
+    public function flushMemory(?string $endpointId = null, ?int $db = null)
     {
         return $this->client->flushMemory($endpointId, $db);
     }
diff --git a/src/Connection/Replication/MasterSlaveReplication.php b/src/Connection/Replication/MasterSlaveReplication.php
index 9d57a5ac3..31897ed3e 100644
--- a/src/Connection/Replication/MasterSlaveReplication.php
+++ b/src/Connection/Replication/MasterSlaveReplication.php
@@ -72,7 +72,7 @@ class MasterSlaveReplication implements ReplicationInterface
     /**
      * {@inheritdoc}
      */
-    public function __construct(ReplicationStrategy $strategy = null)
+    public function __construct(?ReplicationStrategy $strategy = null)
     {
         $this->strategy = $strategy ?: new ReplicationStrategy();
     }
diff --git a/src/Connection/Replication/SentinelReplication.php b/src/Connection/Replication/SentinelReplication.php
index dce18f6b7..573633332 100644
--- a/src/Connection/Replication/SentinelReplication.php
+++ b/src/Connection/Replication/SentinelReplication.php
@@ -117,13 +117,13 @@ class SentinelReplication implements ReplicationInterface
      * @param string                     $service           Name of the service for autodiscovery.
      * @param array                      $sentinels         Sentinel servers connection parameters.
      * @param ConnectionFactoryInterface $connectionFactory Connection factory instance.
-     * @param ReplicationStrategy        $strategy          Replication strategy instance.
+     * @param ReplicationStrategy|null   $strategy          Replication strategy instance.
      */
     public function __construct(
         $service,
         array $sentinels,
         ConnectionFactoryInterface $connectionFactory,
-        ReplicationStrategy $strategy = null
+        ?ReplicationStrategy $strategy = null
     ) {
         $this->sentinels = $sentinels;
         $this->service = $service;
diff --git a/src/Protocol/Text/CompositeProtocolProcessor.php b/src/Protocol/Text/CompositeProtocolProcessor.php
index 3f7df02e5..01c7e4548 100644
--- a/src/Protocol/Text/CompositeProtocolProcessor.php
+++ b/src/Protocol/Text/CompositeProtocolProcessor.php
@@ -37,12 +37,12 @@ class CompositeProtocolProcessor implements ProtocolProcessorInterface
     protected $reader;
 
     /**
-     * @param RequestSerializerInterface $serializer Request serializer.
-     * @param ResponseReaderInterface    $reader     Response reader.
+     * @param RequestSerializerInterface|null $serializer Request serializer.
+     * @param ResponseReaderInterface|null    $reader     Response reader.
      */
     public function __construct(
-        RequestSerializerInterface $serializer = null,
-        ResponseReaderInterface $reader = null
+        ?RequestSerializerInterface $serializer = null,
+        ?ResponseReaderInterface $reader = null
     ) {
         $this->setRequestSerializer($serializer ?: new RequestSerializer());
         $this->setResponseReader($reader ?: new ResponseReader());
diff --git a/src/PubSub/Consumer.php b/src/PubSub/Consumer.php
index b52673232..d32178b6a 100644
--- a/src/PubSub/Consumer.php
+++ b/src/PubSub/Consumer.php
@@ -28,9 +28,9 @@ class Consumer extends AbstractConsumer
 
     /**
      * @param ClientInterface $client  Client instance used by the consumer.
-     * @param array           $options Options for the consumer initialization.
+     * @param array|null      $options Options for the consumer initialization.
      */
-    public function __construct(ClientInterface $client, array $options = null)
+    public function __construct(ClientInterface $client, ?array $options = null)
     {
         $this->checkCapabilities($client);
 
diff --git a/src/Transaction/MultiExec.php b/src/Transaction/MultiExec.php
index 32ac1e123..65b7545bc 100644
--- a/src/Transaction/MultiExec.php
+++ b/src/Transaction/MultiExec.php
@@ -49,9 +49,9 @@ class MultiExec implements ClientContextInterface
 
     /**
      * @param ClientInterface $client  Client instance used by the transaction.
-     * @param array           $options Initialization options.
+     * @param array|null      $options Initialization options.
      */
-    public function __construct(ClientInterface $client, array $options = null)
+    public function __construct(ClientInterface $client, ?array $options = null)
     {
         $this->assertClient($client);
 
diff --git a/tests/PHPUnit/PredisTestCase.php b/tests/PHPUnit/PredisTestCase.php
index 4ad148c15..49ab922a1 100644
--- a/tests/PHPUnit/PredisTestCase.php
+++ b/tests/PHPUnit/PredisTestCase.php
@@ -74,7 +74,7 @@ protected function sleep(float $seconds): void
      *
      * @return RedisCommandConstraint
      */
-    public function isRedisCommand($command = null, array $arguments = null): RedisCommandConstraint
+    public function isRedisCommand($command = null, ?array $arguments = null): RedisCommandConstraint
     {
         return new RedisCommandConstraint($command, $arguments);
     }
@@ -243,7 +243,7 @@ protected function getCommandFactory(): Command\Factory
      *
      * @return Client
      */
-    protected function createClient(array $parameters = null, array $options = null, ?bool $flushdb = true): Client
+    protected function createClient(?array $parameters = null, ?array $options = null, ?bool $flushdb = true): Client
     {
         $parameters = array_merge(
             $this->getDefaultParametersArray(),
diff --git a/tests/PHPUnit/RedisCommandConstraint.php b/tests/PHPUnit/RedisCommandConstraint.php
index d4e0b4ec1..8cb77e18b 100644
--- a/tests/PHPUnit/RedisCommandConstraint.php
+++ b/tests/PHPUnit/RedisCommandConstraint.php
@@ -25,7 +25,7 @@ class RedisCommandConstraint extends \PHPUnit\Framework\Constraint\Constraint
      * @param string|CommandInterface $command   Expected command instance or command ID
      * @param ?array                  $arguments Expected command arguments
      */
-    public function __construct($command, array $arguments = null)
+    public function __construct($command, ?array $arguments = null)
     {
         if ($command instanceof CommandInterface) {
             $this->commandID = strtoupper($command->getId());
diff --git a/tests/Predis/Cluster/PredisStrategyTest.php b/tests/Predis/Cluster/PredisStrategyTest.php
index 70d492f49..f8a20724b 100644
--- a/tests/Predis/Cluster/PredisStrategyTest.php
+++ b/tests/Predis/Cluster/PredisStrategyTest.php
@@ -325,7 +325,7 @@ protected function getClusterStrategy(): StrategyInterface
      *
      * @return array
      */
-    protected function getExpectedCommands(string $type = null): array
+    protected function getExpectedCommands(?string $type = null): array
     {
         $commands = [
             /* commands operating on the key space */
diff --git a/tests/Predis/Cluster/RedisStrategyTest.php b/tests/Predis/Cluster/RedisStrategyTest.php
index d21b0b3bc..36846753a 100644
--- a/tests/Predis/Cluster/RedisStrategyTest.php
+++ b/tests/Predis/Cluster/RedisStrategyTest.php
@@ -348,7 +348,7 @@ protected function getClusterStrategy(): StrategyInterface
      *
      * @return array
      */
-    protected function getExpectedCommands(string $type = null): array
+    protected function getExpectedCommands(?string $type = null): array
     {
         $commands = [
             /* commands operating on the key space */
diff --git a/tests/Predis/CommunicationExceptionTest.php b/tests/Predis/CommunicationExceptionTest.php
index c58e677a0..f6e588bdf 100644
--- a/tests/Predis/CommunicationExceptionTest.php
+++ b/tests/Predis/CommunicationExceptionTest.php
@@ -123,7 +123,7 @@ protected function createMockException(
         Connection\NodeConnectionInterface $connection,
         string $message,
         int $code = 0,
-        Exception $inner = null
+        ?Exception $inner = null
     ) {
         return $this->getMockBuilder('Predis\CommunicationException')
             ->setConstructorArgs([$connection, $message, $code, $inner])
diff --git a/tests/Predis/Connection/ConnectionExceptionTest.php b/tests/Predis/Connection/ConnectionExceptionTest.php
index 066b7b324..e1f06baca 100644
--- a/tests/Predis/Connection/ConnectionExceptionTest.php
+++ b/tests/Predis/Connection/ConnectionExceptionTest.php
@@ -26,7 +26,7 @@ protected function getException(
         NodeConnectionInterface $connection,
         string $message,
         int $code = 0,
-        Exception $inner = null
+        ?Exception $inner = null
     ) {
         return new ConnectionException($connection, $message, $code, $inner);
     }
diff --git a/tests/Predis/Connection/Replication/SentinelReplicationTest.php b/tests/Predis/Connection/Replication/SentinelReplicationTest.php
index 1dcc532c8..521bd3938 100644
--- a/tests/Predis/Connection/Replication/SentinelReplicationTest.php
+++ b/tests/Predis/Connection/Replication/SentinelReplicationTest.php
@@ -1530,7 +1530,7 @@ public function testMethodGetSentinelConnectionAfterSentinelRestart(): void
      *
      * @return SentinelReplication
      */
-    protected function getReplicationConnection(string $service, array $sentinels, Connection\FactoryInterface $factory = null): SentinelReplication
+    protected function getReplicationConnection(string $service, array $sentinels, ?Connection\FactoryInterface $factory = null): SentinelReplication
     {
         $factory = $factory ?: new Connection\Factory();
 
diff --git a/tests/Predis/Protocol/ProtocolExceptionTest.php b/tests/Predis/Protocol/ProtocolExceptionTest.php
index c36fb0c0c..5fe87abc0 100644
--- a/tests/Predis/Protocol/ProtocolExceptionTest.php
+++ b/tests/Predis/Protocol/ProtocolExceptionTest.php
@@ -28,7 +28,7 @@ protected function getException(
         NodeConnectionInterface $connection,
         string $message,
         int $code = 0,
-        Exception $inner = null
+        ?Exception $inner = null
     ): CommunicationException {
         return new ProtocolException($connection, $message, $code, $inner);
     }
diff --git a/tests/Predis/Replication/ReplicationStrategyTest.php b/tests/Predis/Replication/ReplicationStrategyTest.php
index 128bbce4f..ca9ae4bd9 100644
--- a/tests/Predis/Replication/ReplicationStrategyTest.php
+++ b/tests/Predis/Replication/ReplicationStrategyTest.php
@@ -390,7 +390,7 @@ public function testSetLuaScriptAsReadOperationWorksWithScriptCommandAndCallable
      *
      * @return array
      */
-    protected function getExpectedCommands(string $type = null): array
+    protected function getExpectedCommands(?string $type = null): array
     {
         $commands = [
             /* commands operating on the connection */