diff --git a/src/Token/Parser.php b/src/Token/Parser.php
index 530a727c..c8fb3848 100644
--- a/src/Token/Parser.php
+++ b/src/Token/Parser.php
@@ -12,14 +12,13 @@
 use function count;
 use function explode;
 use function is_array;
-use function is_string;
-use function json_encode;
-use function strpos;
-
-use const JSON_THROW_ON_ERROR;
+use function is_numeric;
+use function number_format;
 
 final class Parser implements ParserInterface
 {
+    private const MICROSECOND_PRECISION = 6;
+
     private Decoder $decoder;
 
     public function __construct(Decoder $decoder)
@@ -109,25 +108,29 @@ private function parseClaims(string $data): array
                 continue;
             }
 
-            $date = $claims[$claim];
-
-            $claims[$claim] = $this->convertDate(is_string($date) ? $date : json_encode($date, JSON_THROW_ON_ERROR));
+            $claims[$claim] = $this->convertDate($claims[$claim]);
         }
 
         return $claims;
     }
 
-    /** @throws InvalidTokenStructure */
-    private function convertDate(string $value): DateTimeImmutable
+    /**
+     * @param int|float|string $timestamp
+     *
+     * @throws InvalidTokenStructure
+     */
+    private function convertDate($timestamp): DateTimeImmutable
     {
-        if (strpos($value, '.') === false) {
-            return new DateTimeImmutable('@' . $value);
+        if (! is_numeric($timestamp)) {
+            throw InvalidTokenStructure::dateIsNotParseable($timestamp);
         }
 
-        $date = DateTimeImmutable::createFromFormat('U.u', $value);
+        $normalizedTimestamp = number_format((float) $timestamp, self::MICROSECOND_PRECISION, '.', '');
+
+        $date = DateTimeImmutable::createFromFormat('U.u', $normalizedTimestamp);
 
         if ($date === false) {
-            throw InvalidTokenStructure::dateIsNotParseable($value);
+            throw InvalidTokenStructure::dateIsNotParseable($normalizedTimestamp);
         }
 
         return $date;
diff --git a/test/functional/TimeFractionPrecisionTest.php b/test/functional/TimeFractionPrecisionTest.php
index 4cb0534d..4e197c5c 100644
--- a/test/functional/TimeFractionPrecisionTest.php
+++ b/test/functional/TimeFractionPrecisionTest.php
@@ -5,6 +5,7 @@
 
 use DateTimeImmutable;
 use Lcobucci\JWT\Configuration;
+use Lcobucci\JWT\Encoding\JoseEncoder;
 use Lcobucci\JWT\Token\Plain;
 use PHPUnit\Framework\TestCase;
 
@@ -58,4 +59,42 @@ public function datesWithPotentialRoundingIssues(): iterable
         yield ['1613938511.018045'];
         yield ['1616074725.008455'];
     }
+
+    /**
+     * @test
+     * @dataProvider timeFractionConversions
+     *
+     * @param float|int|string $issuedAt
+     */
+    public function typeConversionDoesNotCauseParsingErrors($issuedAt, string $timeFraction): void
+    {
+        $encoder = new JoseEncoder();
+        $headers = $encoder->base64UrlEncode($encoder->jsonEncode(['typ' => 'JWT', 'alg' => 'none']));
+        $claims  = $encoder->base64UrlEncode($encoder->jsonEncode(['iat' => $issuedAt]));
+
+        $config      = Configuration::forUnsecuredSigner();
+        $parsedToken = $config->parser()->parse($headers . '.' . $claims . '.');
+
+        self::assertInstanceOf(Plain::class, $parsedToken);
+        self::assertSame($timeFraction, $parsedToken->claims()->get('iat')->format('U.u'));
+    }
+
+    /** @return iterable<array{0: float|int|string, 1: string}> */
+    public function timeFractionConversions(): iterable
+    {
+        yield [1616481863.528781890869140625, '1616481863.528782'];
+        yield [1616497608.0510409, '1616497608.051041'];
+        yield [1616536852.1000001, '1616536852.100000'];
+        yield [1616457346.3878131, '1616457346.387813'];
+        yield [1616457346.0, '1616457346.000000'];
+
+        yield [1616457346, '1616457346.000000'];
+
+        yield ['1616481863.528781890869140625', '1616481863.528782'];
+        yield ['1616497608.0510409', '1616497608.051041'];
+        yield ['1616536852.1000001', '1616536852.100000'];
+        yield ['1616457346.3878131', '1616457346.387813'];
+        yield ['1616457346.0', '1616457346.000000'];
+        yield ['1616457346', '1616457346.000000'];
+    }
 }
diff --git a/test/unit/Token/ParserTest.php b/test/unit/Token/ParserTest.php
index 5c1bf90c..70d9893d 100644
--- a/test/unit/Token/ParserTest.php
+++ b/test/unit/Token/ParserTest.php
@@ -485,6 +485,49 @@ public function parseMustConvertDateClaimsToObjects(): void
         );
     }
 
+    /**
+     * @test
+     *
+     * @covers ::__construct
+     * @covers ::parse
+     * @covers ::splitJwt
+     * @covers ::parseHeader
+     * @covers ::parseClaims
+     * @covers ::parseSignature
+     * @covers ::convertDate
+     *
+     * @uses \Lcobucci\JWT\Token\Plain
+     * @uses \Lcobucci\JWT\Token\Signature
+     * @uses \Lcobucci\JWT\Token\DataSet
+     */
+    public function parseMustConvertStringDates(): void
+    {
+        $data = [RegisteredClaims::NOT_BEFORE => '1486930757.000000'];
+
+        $this->decoder->expects(self::exactly(2))
+            ->method('base64UrlDecode')
+            ->withConsecutive(['a'], ['b'])
+            ->willReturnOnConsecutiveCalls('a_dec', 'b_dec');
+
+        $this->decoder->expects(self::exactly(2))
+            ->method('jsonDecode')
+            ->withConsecutive(['a_dec'], ['b_dec'])
+            ->willReturnOnConsecutiveCalls(
+                ['typ' => 'JWT', 'alg' => 'HS256'],
+                $data
+            );
+
+        $token = $this->createParser()->parse('a.b.');
+        self::assertInstanceOf(Plain::class, $token);
+
+        $claims = $token->claims();
+
+        self::assertEquals(
+            DateTimeImmutable::createFromFormat('U.u', '1486930757.000000'),
+            $claims->get(RegisteredClaims::NOT_BEFORE)
+        );
+    }
+
     /**
      * @test
      *
@@ -522,4 +565,41 @@ public function parseShouldRaiseExceptionOnInvalidDate(): void
         $this->expectExceptionMessage('Value is not in the allowed date format: 14/10/2018 10:50:10.10 UTC');
         $this->createParser()->parse('a.b.');
     }
+
+    /**
+     * @test
+     *
+     * @covers ::__construct
+     * @covers ::parse
+     * @covers ::splitJwt
+     * @covers ::parseHeader
+     * @covers ::parseClaims
+     * @covers ::parseSignature
+     * @covers ::convertDate
+     * @covers \Lcobucci\JWT\Token\InvalidTokenStructure
+     *
+     * @uses \Lcobucci\JWT\Token\Plain
+     * @uses \Lcobucci\JWT\Token\Signature
+     * @uses \Lcobucci\JWT\Token\DataSet
+     */
+    public function parseShouldRaiseExceptionOnTimestampBeyondDateTimeImmutableRange(): void
+    {
+        $data = [RegisteredClaims::ISSUED_AT => -10000000000 ** 5];
+
+        $this->decoder->expects(self::exactly(2))
+            ->method('base64UrlDecode')
+            ->withConsecutive(['a'], ['b'])
+            ->willReturnOnConsecutiveCalls('a_dec', 'b_dec');
+
+        $this->decoder->expects(self::exactly(2))
+            ->method('jsonDecode')
+            ->withConsecutive(['a_dec'], ['b_dec'])
+            ->willReturnOnConsecutiveCalls(
+                ['typ' => 'JWT', 'alg' => 'HS256'],
+                $data
+            );
+
+        $this->expectException(InvalidTokenStructure::class);
+        $this->createParser()->parse('a.b.');
+    }
 }