diff --git a/composer.json b/composer.json
index 4cddbf17..eb394633 100644
--- a/composer.json
+++ b/composer.json
@@ -16,8 +16,8 @@
         "php": "^8.0 || ^7.4",
         "ext-json": "*",
         "ext-tokenizer": "*",
-        "symfony/console": "^6.0 || ^5.0 || ^4.0 || ^3.4",
-        "symfony/var-dumper": "^6.0 || ^5.0 || ^4.0 || ^3.4",
+        "symfony/console": "^7.0 || ^6.0 || ^5.0 || ^4.0 || ^3.4",
+        "symfony/var-dumper": "^7.0 || ^6.0 || ^5.0 || ^4.0 || ^3.4",
         "nikic/php-parser": "^4.0"
     },
     "require-dev": {
diff --git a/src/Command/BufferCommand.php b/src/Command/BufferCommand.php
index 81d8ff91..8348aee6 100644
--- a/src/Command/BufferCommand.php
+++ b/src/Command/BufferCommand.php
@@ -50,7 +50,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $app = $this->getApplication();
         if (!$app instanceof \Psy\Shell) {
diff --git a/src/Command/ClearCommand.php b/src/Command/ClearCommand.php
index baca9af0..42a66b0f 100644
--- a/src/Command/ClearCommand.php
+++ b/src/Command/ClearCommand.php
@@ -44,7 +44,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $output->write(\sprintf('%c[2J%c[0;0f', 27, 27));
 
diff --git a/src/Command/Command.php b/src/Command/Command.php
index 09750884..0d18d2c6 100644
--- a/src/Command/Command.php
+++ b/src/Command/Command.php
@@ -30,13 +30,13 @@ abstract class Command extends BaseCommand
      *
      * @api
      */
-    public function setApplication(Application $application = null)
+    public function setApplication(Application $application = null): void
     {
         if ($application !== null && !$application instanceof Shell) {
             throw new \InvalidArgumentException('PsySH Commands require an instance of Psy\Shell');
         }
 
-        return parent::setApplication($application);
+        parent::setApplication($application);
     }
 
     /**
diff --git a/src/Command/DocCommand.php b/src/Command/DocCommand.php
index 2eb715fc..1650ccf6 100644
--- a/src/Command/DocCommand.php
+++ b/src/Command/DocCommand.php
@@ -62,7 +62,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $value = $input->getArgument('target');
         if (ReflectionLanguageConstruct::isLanguageConstruct($value)) {
diff --git a/src/Command/DumpCommand.php b/src/Command/DumpCommand.php
index c3bc604d..88ddbe26 100644
--- a/src/Command/DumpCommand.php
+++ b/src/Command/DumpCommand.php
@@ -69,7 +69,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $depth = $input->getOption('depth');
         $target = $this->resolveCode($input->getArgument('target'));
diff --git a/src/Command/EditCommand.php b/src/Command/EditCommand.php
index af2914d5..7612b3de 100644
--- a/src/Command/EditCommand.php
+++ b/src/Command/EditCommand.php
@@ -79,7 +79,7 @@ protected function configure()
      * @throws \InvalidArgumentException when both exec and no-exec flags are given or if a given variable is not found in the current context
      * @throws \UnexpectedValueException if file_get_contents on the edited file returns false instead of a string
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         if ($input->getOption('exec') &&
             $input->getOption('no-exec')) {
diff --git a/src/Command/ExitCommand.php b/src/Command/ExitCommand.php
index 01f72d9f..6552e288 100644
--- a/src/Command/ExitCommand.php
+++ b/src/Command/ExitCommand.php
@@ -47,7 +47,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         throw new BreakException('Goodbye');
     }
diff --git a/src/Command/HelpCommand.php b/src/Command/HelpCommand.php
index 9443c550..13ea3483 100644
--- a/src/Command/HelpCommand.php
+++ b/src/Command/HelpCommand.php
@@ -55,7 +55,7 @@ public function setCommand(Command $command)
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         if ($this->command !== null) {
             // help for an individual command
diff --git a/src/Command/HistoryCommand.php b/src/Command/HistoryCommand.php
index 94306e40..cf5f29b9 100644
--- a/src/Command/HistoryCommand.php
+++ b/src/Command/HistoryCommand.php
@@ -93,7 +93,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $this->validateOnlyOne($input, ['show', 'head', 'tail']);
         $this->validateOnlyOne($input, ['save', 'replay', 'clear']);
diff --git a/src/Command/ListCommand.php b/src/Command/ListCommand.php
index 6910d903..1982aa4c 100644
--- a/src/Command/ListCommand.php
+++ b/src/Command/ListCommand.php
@@ -114,7 +114,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $this->validateInput($input);
         $this->initEnumerators();
diff --git a/src/Command/ParseCommand.php b/src/Command/ParseCommand.php
index a62be67f..205cc362 100644
--- a/src/Command/ParseCommand.php
+++ b/src/Command/ParseCommand.php
@@ -119,7 +119,7 @@ protected function configure()
     /**
      * {@inheritdoc}
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $code = $input->getArgument('code');
         $parserKind = $input->getOption('kind');
diff --git a/src/Command/PsyVersionCommand.php b/src/Command/PsyVersionCommand.php
index 44e75283..959a9a78 100644
--- a/src/Command/PsyVersionCommand.php
+++ b/src/Command/PsyVersionCommand.php
@@ -34,7 +34,7 @@ protected function configure()
     /**
      * {@inheritdoc}
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $output->writeln($this->getApplication()->getVersion());
 
diff --git a/src/Command/ShowCommand.php b/src/Command/ShowCommand.php
index d8a93c0c..4d721d72 100644
--- a/src/Command/ShowCommand.php
+++ b/src/Command/ShowCommand.php
@@ -64,7 +64,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         // n.b. As far as I can tell, InputInterface doesn't want to tell me
         // whether an option with an optional value was actually passed. If you
diff --git a/src/Command/SudoCommand.php b/src/Command/SudoCommand.php
index b398bd89..bd08d14b 100644
--- a/src/Command/SudoCommand.php
+++ b/src/Command/SudoCommand.php
@@ -96,7 +96,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $code = $input->getArgument('code');
 
diff --git a/src/Command/ThrowUpCommand.php b/src/Command/ThrowUpCommand.php
index 5653b81e..bb5bf5dd 100644
--- a/src/Command/ThrowUpCommand.php
+++ b/src/Command/ThrowUpCommand.php
@@ -75,7 +75,7 @@ protected function configure()
      *
      * @throws \InvalidArgumentException if there is no exception to throw
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $args = $this->prepareArgs($input->getArgument('exception'));
         $throwStmt = new Throw_(new New_(new FullyQualifiedName(ThrowUpException::class), $args));
diff --git a/src/Command/TimeitCommand.php b/src/Command/TimeitCommand.php
index 3236bf01..3a2efee1 100644
--- a/src/Command/TimeitCommand.php
+++ b/src/Command/TimeitCommand.php
@@ -78,7 +78,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $code = $input->getArgument('code');
         $num = (int) ($input->getOption('num') ?: 1);
diff --git a/src/Command/TraceCommand.php b/src/Command/TraceCommand.php
index 8ba1ad86..411237e1 100644
--- a/src/Command/TraceCommand.php
+++ b/src/Command/TraceCommand.php
@@ -71,7 +71,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $this->filter->bind($input);
         $trace = $this->getBacktrace(new \Exception(), $input->getOption('num'), $input->getOption('include-psy'));
diff --git a/src/Command/WhereamiCommand.php b/src/Command/WhereamiCommand.php
index 2b0280ea..b7d569be 100644
--- a/src/Command/WhereamiCommand.php
+++ b/src/Command/WhereamiCommand.php
@@ -109,7 +109,7 @@ protected function fileInfo(): array
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $info = $this->fileInfo();
         $num = $input->getOption('num');
diff --git a/src/Command/WtfCommand.php b/src/Command/WtfCommand.php
index 3d967fc5..6e2472c0 100644
--- a/src/Command/WtfCommand.php
+++ b/src/Command/WtfCommand.php
@@ -84,7 +84,7 @@ protected function configure()
      *
      * @return int 0 if everything went fine, or an exit code
      */
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         $this->filter->bind($input);
 
diff --git a/src/Input/ShellInput.php b/src/Input/ShellInput.php
index a185c6fd..9b8bf81d 100644
--- a/src/Input/ShellInput.php
+++ b/src/Input/ShellInput.php
@@ -47,7 +47,7 @@ public function __construct(string $input)
      *
      * @throws \InvalidArgumentException if $definition has CodeArgument before the final argument position
      */
-    public function bind(InputDefinition $definition)
+    public function bind(InputDefinition $definition): void
     {
         $hasCodeArgument = false;
 
@@ -68,7 +68,7 @@ public function bind(InputDefinition $definition)
 
         $this->hasCodeArgument = $hasCodeArgument;
 
-        return parent::bind($definition);
+        parent::bind($definition);
     }
 
     /**
@@ -121,7 +121,7 @@ private function tokenize(string $input): array
     /**
      * Same as parent, but with some bonus handling for code arguments.
      */
-    protected function parse()
+    protected function parse(): void
     {
         $parseOptions = true;
         $this->parsed = $this->tokenPairs;
diff --git a/src/Output/ProcOutputPager.php b/src/Output/ProcOutputPager.php
index aeaff368..42e40db5 100644
--- a/src/Output/ProcOutputPager.php
+++ b/src/Output/ProcOutputPager.php
@@ -48,7 +48,7 @@ public function __construct(StreamOutput $output, string $cmd = 'less -R -F -X')
      *
      * @throws \RuntimeException When unable to write output (should never happen)
      */
-    public function doWrite($message, $newline)
+    public function doWrite($message, $newline): void
     {
         $pipe = $this->getPipe();
         if (false === @\fwrite($pipe, $message.($newline ? \PHP_EOL : ''))) {
diff --git a/src/Output/ShellOutput.php b/src/Output/ShellOutput.php
index 543baccb..2ef575dc 100644
--- a/src/Output/ShellOutput.php
+++ b/src/Output/ShellOutput.php
@@ -119,7 +119,7 @@ public function stopPaging()
      * @param bool         $newline  Whether to add a newline or not
      * @param int          $type     The type of output
      */
-    public function write($messages, $newline = false, $type = 0)
+    public function write($messages, $newline = false, $type = 0): void
     {
         if ($this->getVerbosity() === self::VERBOSITY_QUIET) {
             return;
@@ -154,7 +154,7 @@ public function write($messages, $newline = false, $type = 0)
      * @param string $message A message to write to the output
      * @param bool   $newline Whether to add a newline or not
      */
-    public function doWrite($message, $newline)
+    public function doWrite($message, $newline): void
     {
         if ($this->paging > 0) {
             $this->pager->doWrite($message, $newline);
diff --git a/src/Shell.php b/src/Shell.php
index f3cfde9b..ad5dc2a2 100644
--- a/src/Shell.php
+++ b/src/Shell.php
@@ -436,7 +436,7 @@ private function doNonInteractiveRun(bool $rawOutput): int
     /**
      * Configures the input and output instances based on the user arguments and options.
      */
-    protected function configureIO(InputInterface $input, OutputInterface $output)
+    protected function configureIO(InputInterface $input, OutputInterface $output): void
     {
         // @todo overrides via environment variables (or should these happen in config? ... probably config)
         $input->setInteractive($this->config->getInputInteractive());
diff --git a/src/VarDumper/Dumper.php b/src/VarDumper/Dumper.php
index 0eacbc93..def61d4a 100644
--- a/src/VarDumper/Dumper.php
+++ b/src/VarDumper/Dumper.php
@@ -23,9 +23,9 @@ class Dumper extends CliDumper
     private $formatter;
     private $forceArrayIndexes;
 
-    const ONLY_CONTROL_CHARS = '/^[\x00-\x1F\x7F]+$/';
-    const CONTROL_CHARS = '/([\x00-\x1F\x7F]+)/';
-    const CONTROL_CHARS_MAP = [
+    private const ONLY_CONTROL_CHARS = '/^[\x00-\x1F\x7F]+$/';
+    private const CONTROL_CHARS = '/([\x00-\x1F\x7F]+)/';
+    private const CONTROL_CHARS_MAP = [
         "\0"   => '\0',
         "\t"   => '\t',
         "\n"   => '\n',
@@ -46,7 +46,7 @@ public function __construct(OutputFormatter $formatter, $forceArrayIndexes = fal
     /**
      * {@inheritdoc}
      */
-    public function enterHash(Cursor $cursor, $type, $class, $hasChild)
+    public function enterHash(Cursor $cursor, $type, $class, $hasChild): void
     {
         if (Cursor::HASH_INDEXED === $type || Cursor::HASH_ASSOC === $type) {
             $class = 0;
@@ -57,7 +57,7 @@ public function enterHash(Cursor $cursor, $type, $class, $hasChild)
     /**
      * {@inheritdoc}
      */
-    protected function dumpKey(Cursor $cursor)
+    protected function dumpKey(Cursor $cursor): void
     {
         if ($this->forceArrayIndexes || Cursor::HASH_INDEXED !== $cursor->hashType) {
             parent::dumpKey($cursor);
@@ -97,7 +97,7 @@ protected function style($style, $value, $attr = []): string
     /**
      * {@inheritdoc}
      */
-    protected function dumpLine($depth, $endOfValue = false)
+    protected function dumpLine($depth, $endOfValue = false): void
     {
         if ($endOfValue && 0 < $depth) {
             $this->line .= ',';