diff --git a/src/Symfony/Component/VarDumper/Caster/AmqpCaster.php b/src/Symfony/Component/VarDumper/Caster/AmqpCaster.php
index 19bdc29525eab..f1f85b7e2b7c0 100644
--- a/src/Symfony/Component/VarDumper/Caster/AmqpCaster.php
+++ b/src/Symfony/Component/VarDumper/Caster/AmqpCaster.php
@@ -191,7 +191,7 @@ public static function castEnvelope(\AMQPEnvelope $c, array $a, Stub $stub, $isN
         return $a;
     }
 
-    private static function extractFlags($flags)
+    private static function extractFlags(int $flags): ConstStub
     {
         $flagsArray = [];
 
diff --git a/src/Symfony/Component/VarDumper/Caster/ArgsStub.php b/src/Symfony/Component/VarDumper/Caster/ArgsStub.php
index 1ca7a86d3a572..591c7e2a844a0 100644
--- a/src/Symfony/Component/VarDumper/Caster/ArgsStub.php
+++ b/src/Symfony/Component/VarDumper/Caster/ArgsStub.php
@@ -49,7 +49,7 @@ public function __construct(array $args, string $function, ?string $class)
         }
     }
 
-    private static function getParameters($function, $class)
+    private static function getParameters(string $function, ?string $class): array
     {
         if (isset(self::$parameters[$k = $class.'::'.$function])) {
             return self::$parameters[$k];
diff --git a/src/Symfony/Component/VarDumper/Caster/DateCaster.php b/src/Symfony/Component/VarDumper/Caster/DateCaster.php
index 4e83a9935e40a..0cc95a8b161ef 100644
--- a/src/Symfony/Component/VarDumper/Caster/DateCaster.php
+++ b/src/Symfony/Component/VarDumper/Caster/DateCaster.php
@@ -110,12 +110,12 @@ public static function castPeriod(\DatePeriod $p, array $a, Stub $stub, $isNeste
         return $filter & Caster::EXCLUDE_VERBOSE ? $p : $p + $a;
     }
 
-    private static function formatDateTime(\DateTimeInterface $d, $extra = '')
+    private static function formatDateTime(\DateTimeInterface $d, string $extra = ''): string
     {
         return $d->format('Y-m-d H:i:'.self::formatSeconds($d->format('s'), $d->format('u')).$extra);
     }
 
-    private static function formatSeconds($s, $us)
+    private static function formatSeconds(string $s, string $us): string
     {
         return sprintf('%02d.%s', $s, 0 === ($len = \strlen($t = rtrim($us, '0'))) ? '0' : ($len <= 3 ? str_pad($t, 3, '0') : $us));
     }
diff --git a/src/Symfony/Component/VarDumper/Caster/ExceptionCaster.php b/src/Symfony/Component/VarDumper/Caster/ExceptionCaster.php
index 60cffcb6b73a9..5c2ae7daee3ff 100644
--- a/src/Symfony/Component/VarDumper/Caster/ExceptionCaster.php
+++ b/src/Symfony/Component/VarDumper/Caster/ExceptionCaster.php
@@ -261,7 +261,7 @@ public static function castFrameStub(FrameStub $frame, array $a, Stub $stub, $is
         return $a;
     }
 
-    private static function filterExceptionArray($xClass, array $a, $xPrefix, $filter)
+    private static function filterExceptionArray(string $xClass, array $a, string $xPrefix, int $filter): array
     {
         if (isset($a[$xPrefix.'trace'])) {
             $trace = $a[$xPrefix.'trace'];
@@ -294,7 +294,7 @@ private static function filterExceptionArray($xClass, array $a, $xPrefix, $filte
         return $a;
     }
 
-    private static function traceUnshift(&$trace, $class, $file, $line)
+    private static function traceUnshift(array &$trace, ?string $class, string $file, int $line): void
     {
         if (isset($trace[0]['file'], $trace[0]['line']) && $trace[0]['file'] === $file && $trace[0]['line'] === $line) {
             return;
@@ -306,7 +306,7 @@ private static function traceUnshift(&$trace, $class, $file, $line)
         ]);
     }
 
-    private static function extractSource($srcLines, $line, $srcContext, $title, $lang, $file = null)
+    private static function extractSource(string $srcLines, int $line, int $srcContext, ?string $title, string $lang, string $file = null): EnumStub
     {
         $srcLines = explode("\n", $srcLines);
         $src = [];