diff --git a/src/Symfony/Component/Validator/Constraints/CharsetValidator.php b/src/Symfony/Component/Validator/Constraints/CharsetValidator.php
index 3e5de79d2eb48..5cde6ae90fd96 100644
--- a/src/Symfony/Component/Validator/Constraints/CharsetValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/CharsetValidator.php
@@ -35,9 +35,9 @@ public function validate(mixed $value, Constraint $constraint): void
             throw new UnexpectedValueException($value, 'string');
         }
 
-        if (!\in_array($detected = mb_detect_encoding($value, $constraint->encodings, true), (array) $constraint->encodings, true)) {
+        if (!\in_array(mb_detect_encoding($value, $constraint->encodings, true), (array) $constraint->encodings, true)) {
             $this->context->buildViolation($constraint->message)
-                ->setParameter('{{ detected }}', $detected)
+                ->setParameter('{{ detected }}', mb_detect_encoding($value, strict: true))
                 ->setParameter('{{ encodings }}', implode(', ', $constraint->encodings))
                 ->setCode(Charset::BAD_ENCODING_ERROR)
                 ->addViolation();
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/CharsetValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/CharsetValidatorTest.php
index 76470b9370dee..88998dcdbcad0 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/CharsetValidatorTest.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/CharsetValidatorTest.php
@@ -42,7 +42,7 @@ public function testInvalidValues(string $value, array $encodings)
         $this->validator->validate($value, new Charset(encodings: $encodings));
 
         $this->buildViolation('The detected character encoding is invalid ({{ detected }}). Allowed encodings are {{ encodings }}.')
-            ->setParameter('{{ detected }}', mb_detect_encoding($value, $encodings, true))
+            ->setParameter('{{ detected }}', 'UTF-8')
             ->setParameter('{{ encodings }}', implode(', ', $encodings))
             ->setCode(Charset::BAD_ENCODING_ERROR)
             ->assertRaised();