diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index f60e71d..eb08ee2 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -34,6 +34,7 @@ jobs:
           - "8.1"
           - "8.2"
           - "8.3"
+          - "8.4"
         postgres-version:
           - "16"
         extension:
@@ -68,7 +69,7 @@ jobs:
           ini-values: "zend.assertions=1"
 
       - name: "Install dependencies with Composer"
-        uses: "ramsey/composer-install@v2"
+        uses: "ramsey/composer-install@v3"
         with:
           dependency-versions: "${{ matrix.dependencies }}"
           composer-options: "--ignore-platform-req=php+"
@@ -132,7 +133,7 @@ jobs:
           ini-values: "zend.assertions=1"
 
       - name: "Install dependencies with Composer"
-        uses: "ramsey/composer-install@v2"
+        uses: "ramsey/composer-install@v3"
         with:
           composer-options: "--ignore-platform-req=php+"
 
@@ -195,7 +196,7 @@ jobs:
           extensions: "${{ matrix.extension }}"
 
       - name: "Install dependencies with Composer"
-        uses: "ramsey/composer-install@v2"
+        uses: "ramsey/composer-install@v3"
         with:
           composer-options: "--ignore-platform-req=php+"
 
@@ -256,7 +257,7 @@ jobs:
           extensions: "${{ matrix.extension }}"
 
       - name: "Install dependencies with Composer"
-        uses: "ramsey/composer-install@v2"
+        uses: "ramsey/composer-install@v3"
         with:
           composer-options: "--ignore-platform-req=php+"
 
@@ -314,7 +315,7 @@ jobs:
           extensions: "${{ matrix.extension }}-5.10.0"
 
       - name: "Install dependencies with Composer"
-        uses: "ramsey/composer-install@v2"
+        uses: "ramsey/composer-install@v3"
         with:
           composer-options: "--ignore-platform-req=php+"
 
@@ -363,7 +364,7 @@ jobs:
           ini-values: "zend.assertions=1"
 
       - name: "Install dependencies with Composer"
-        uses: "ramsey/composer-install@v2"
+        uses: "ramsey/composer-install@v3"
         with:
           composer-options: "--ignore-platform-req=php+"
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 188d6c1..7f7528e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## Next
+
+* [feature] ⭐️ PHP 8.4 support.
+
 ## 1.6.2
 
 * [feature] ⭐️ Allow `Converter::fromSql()` `$type` parameter to be a user-given callback.
diff --git a/dev.sh b/dev.sh
index 771bcc7..a9e6eb2 100755
--- a/dev.sh
+++ b/dev.sh
@@ -5,7 +5,7 @@ GREEN='\033[0;32m'
 NC='\033[0m' # No Color
 
 # PHP version.
-PHPVER="8-1"
+PHPVER="8-4"
 # Extra parameters passed to all docker command lines.
 EXTRA_DOCKER_ENV=""
 
@@ -21,11 +21,17 @@ while getopts ":xp:l" opt; do
         p)
             p=${OPTARG}
             case "${OPTARG}" in
+                "8.1")
+                    PHPVER="8-1"
+                    ;;
                 "8.3")
                     PHPVER="8-3"
                     ;;
+                "8.4")
+                    PHPVER="8-4"
+                    ;;
                 *)
-                    PHPVER="8-1"
+                    PHPVER="8-4"
                     ;;
             esac
             ;;
diff --git a/docker-compose.yaml b/docker-compose.yaml
index 40a2c54..08d741a 100644
--- a/docker-compose.yaml
+++ b/docker-compose.yaml
@@ -23,6 +23,18 @@ services:
             XDEBUG_MODE: "${XDEBUG_MODE:-debug}"
         extra_hosts:
             - "host.docker.internal:host-gateway"
+    phpunit-8-4:
+        build: ./docker/php-8.4
+        networks:
+            - query-builder-test
+        volumes:
+            - ./:/var/www
+        environment:
+            PHP_IDE_CONFIG: ${PHP_IDE_CONFIG:-serverName=docker}
+            XDEBUG_CONFIG: "client_host=host.docker.internal client_port=9000 log=/tmp/xdebug/xdebug.log output_dir=/tmp/xdebug start_with_request=trigger"
+            XDEBUG_MODE: "${XDEBUG_MODE:-debug}"
+        extra_hosts:
+            - "host.docker.internal:host-gateway"
     mysql57:
         image: mysql:5.7
         restart: 'no'
diff --git a/src/Bridge/AbstractBridge.php b/src/Bridge/AbstractBridge.php
index d83a103..d0d1801 100644
--- a/src/Bridge/AbstractBridge.php
+++ b/src/Bridge/AbstractBridge.php
@@ -251,7 +251,7 @@ public function getDefaultSchema(): string
     abstract protected function doExecuteQuery(string $expression, array $arguments = []): Result;
 
     #[\Override]
-    public function executeQuery(string|Expression $expression = null, mixed $arguments = null): Result
+    public function executeQuery(null|string|Expression $expression = null, mixed $arguments = null): Result
     {
         if (\is_string($expression)) {
             $expression = new Raw($expression, $arguments);
@@ -277,7 +277,7 @@ public function executeQuery(string|Expression $expression = null, mixed $argume
     abstract protected function doExecuteStatement(string $expression, array $arguments = []): ?int;
 
     #[\Override]
-    public function executeStatement(string|Expression $expression = null, mixed $arguments = null): ?int
+    public function executeStatement(null|string|Expression $expression = null, mixed $arguments = null): ?int
     {
         if (\is_string($expression)) {
             $expression = new Raw($expression, $arguments);
diff --git a/src/DatabaseSession.php b/src/DatabaseSession.php
index 1d0c27b..de1d928 100644
--- a/src/DatabaseSession.php
+++ b/src/DatabaseSession.php
@@ -74,7 +74,7 @@ public function vendorVersionIs(string $version, string $operator = '>='): bool;
     /**
      * Execute query and return result.
      */
-    public function executeQuery(string|Expression $expression = null, mixed $arguments = null): Result;
+    public function executeQuery(null|string|Expression $expression = null, mixed $arguments = null): Result;
 
     /**
      * Execute query and return affected row count if possible.
@@ -82,7 +82,7 @@ public function executeQuery(string|Expression $expression = null, mixed $argume
      * @return null|int
      *   Affected row count if applyable and driver supports it.
      */
-    public function executeStatement(string|Expression $expression = null, mixed $arguments = null): ?int;
+    public function executeStatement(null|string|Expression $expression = null, mixed $arguments = null): ?int;
 
     /**
      * Creates a new transaction.
diff --git a/src/DefaultQueryBuilder.php b/src/DefaultQueryBuilder.php
index b1be012..d43814d 100644
--- a/src/DefaultQueryBuilder.php
+++ b/src/DefaultQueryBuilder.php
@@ -68,7 +68,7 @@ public function delete(string|Expression $table, ?string $alias = null): Delete
     }
 
     #[\Override]
-    public function raw(string $expression = null, mixed $arguments = null, bool $returns = false): RawQuery
+    public function raw(null|string $expression = null, mixed $arguments = null, bool $returns = false): RawQuery
     {
         $ret = new RawQuery($expression, $arguments, $returns);
         $this->prepareQuery($ret);
diff --git a/src/Platform/Transaction/AbstractTransaction.php b/src/Platform/Transaction/AbstractTransaction.php
index 94723d4..a21506a 100644
--- a/src/Platform/Transaction/AbstractTransaction.php
+++ b/src/Platform/Transaction/AbstractTransaction.php
@@ -176,7 +176,7 @@ public function deferred($constraint = null): static
     }
 
     #[\Override]
-    public function savepoint(string $name = null): TransactionSavepoint
+    public function savepoint(null|string $name = null): TransactionSavepoint
     {
         if (!$this->started) {
             throw new TransactionError(\sprintf("can not commit a non-running transaction"));
diff --git a/src/Query/Partial/FromClauseTrait.php b/src/Query/Partial/FromClauseTrait.php
index da5c560..0c3082f 100644
--- a/src/Query/Partial/FromClauseTrait.php
+++ b/src/Query/Partial/FromClauseTrait.php
@@ -109,7 +109,7 @@ final public function leftJoin(string|Expression $table, $condition = null, ?str
     /**
      * Add inner statement and return the associated Where.
      */
-    final public function innerJoinWhere(string|Expression $table, string $alias = null): Where
+    final public function innerJoinWhere(string|Expression $table, null|string $alias = null): Where
     {
         return $this->joinWhere($table, $alias, Query::JOIN_INNER);
     }
@@ -117,7 +117,7 @@ final public function innerJoinWhere(string|Expression $table, string $alias = n
     /**
      * Add left outer join statement and return the associated Where.
      */
-    final public function leftJoinWhere(string|Expression $table, string $alias = null): Where
+    final public function leftJoinWhere(string|Expression $table, null|string $alias = null): Where
     {
         return $this->joinWhere($table, $alias, Query::JOIN_LEFT_OUTER);
     }
diff --git a/src/QueryBuilder.php b/src/QueryBuilder.php
index 36b5802..44db29c 100644
--- a/src/QueryBuilder.php
+++ b/src/QueryBuilder.php
@@ -44,7 +44,7 @@ public function delete(string|Expression $table, ?string $alias = null): Delete;
     /**
      * Create raw SQL query.
      */
-    public function raw(string $expression = null, mixed $arguments = null, bool $returns = false): RawQuery;
+    public function raw(null|string $expression = null, mixed $arguments = null, bool $returns = false): RawQuery;
 
     /**
      * Get the expression factory.
diff --git a/src/Result/IterableResult.php b/src/Result/IterableResult.php
index 5948c68..00f6c07 100644
--- a/src/Result/IterableResult.php
+++ b/src/Result/IterableResult.php
@@ -15,7 +15,7 @@ class IterableResult extends AbstractResult
     public function __construct(
         iterable $data,
         private ?int $rowCount = null,
-        callable $freeCallback = null,
+        null|callable $freeCallback = null,
     ) {
         parent::__construct(false);
 
diff --git a/src/Transaction/Transaction.php b/src/Transaction/Transaction.php
index 5d9c8a1..f6deae9 100644
--- a/src/Transaction/Transaction.php
+++ b/src/Transaction/Transaction.php
@@ -34,27 +34,27 @@ public function start(): static;
     /**
      * Set as immediate all or a set of constraints.
      *
-     * @param string|string[] $constraint
+     * @param null|string|string[] $constraint
      *   If set to null, all constraints are set immediate
      *   If a string or a string array, only the given constraint
      *   names are set as immediate.
      */
-    public function immediate(string|array $constraint = null): static;
+    public function immediate(null|string|array $constraint = null): static;
 
     /**
      * Defer all or a set of constraints.
      *
-     * @param string|string[] $constraint
+     * @param null|string|string[] $constraint
      *   If set to null, all constraints are set immediate
      *   If a string or a string array, only the given constraint
      *   names are set as immediate.
      */
-    public function deferred(string|array $constraint = null): static;
+    public function deferred(null|string|array $constraint = null): static;
 
     /**
      * Creates a savepoint and return its name.
      *
-     * @param string $name
+     * @param null|string $name
      *   Optional user given savepoint name, if none provided a name will be
      *   automatically computed using a serial.
      *
@@ -64,7 +64,7 @@ public function deferred(string|array $constraint = null): static;
      * @return TransactionSavepoint
      *   The nested transaction.
      */
-    public function savepoint(string $name = null): TransactionSavepoint;
+    public function savepoint(null|string $name = null): TransactionSavepoint;
 
     /**
      * Is transaction nested (ie. is a savepoint).
diff --git a/src/Type/Type.php b/src/Type/Type.php
index 0454493..05b71dd 100644
--- a/src/Type/Type.php
+++ b/src/Type/Type.php
@@ -53,7 +53,7 @@ public static function bool(): self
     /**
      * Padded fixed-with character string.
      */
-    public static function char(int $length = null): self
+    public static function char(null|int $length = null): self
     {
         return new self(internal: InternalType::CHAR, length: $length);
     }
@@ -79,7 +79,7 @@ public static function dateInterval(): self
     /**
      * Decimal/numeric arbitrary precision numeric value.
      */
-    public static function decimal(?int $precision = null, int $scale = null): self
+    public static function decimal(null|int $precision = null, null|int $scale = null): self
     {
         return new self(internal: InternalType::DECIMAL, precision: $precision, scale: $scale);
     }
diff --git a/src/Where.php b/src/Where.php
index de55162..2839296 100644
--- a/src/Where.php
+++ b/src/Where.php
@@ -148,7 +148,7 @@ protected function addNotExpression(mixed $expression): void
     /**
      * Add a single raw SQL expression.
      */
-    public function withRaw(string $expression, mixed $arguments = null): static
+    public function withRaw(null|string $expression, mixed $arguments = null): static
     {
         $this->addExpression(new Raw($expression, $arguments));
 
diff --git a/src/Writer/Writer.php b/src/Writer/Writer.php
index e9cb594..474250f 100644
--- a/src/Writer/Writer.php
+++ b/src/Writer/Writer.php
@@ -616,7 +616,7 @@ protected function doFormatJoin(
         array $join,
         bool $transformFirstJoinAsFrom = false,
         ?string $fromPrefix = null,
-        Query $query = null
+        null|Query $query = null
     ): string {
         if (!$join) {
             return '';