diff --git a/src/Symfony/Component/Clock/MockClock.php b/src/Symfony/Component/Clock/MockClock.php
index 08ac57b2c1d9c..4835b96029157 100644
--- a/src/Symfony/Component/Clock/MockClock.php
+++ b/src/Symfony/Component/Clock/MockClock.php
@@ -40,21 +40,11 @@ public function now(): \DateTimeImmutable
 
     public function sleep(float|int $seconds): void
     {
-        $now = explode('.', $this->now->format('U.u'));
-
-        if (0 < $s = (int) $seconds) {
-            $now[0] += $s;
-        }
-
-        if (0 < ($us = $seconds - $s) && 1E6 <= $now[1] += $us * 1E6) {
-            ++$now[0];
-            $now[1] -= 1E6;
-        }
-
-        $datetime = '@'.$now[0].'.'.str_pad($now[1], 6, '0', \STR_PAD_LEFT);
+        $now = (float) $this->now->format('Uu') + $seconds * 1e6;
+        $now = substr_replace(sprintf('@%07.0F', $now), '.', -6, 0);
         $timezone = $this->now->getTimezone();
 
-        $this->now = (new \DateTimeImmutable($datetime, $timezone))->setTimezone($timezone);
+        $this->now = (new \DateTimeImmutable($now, $timezone))->setTimezone($timezone);
     }
 
     public function withTimeZone(\DateTimeZone|string $timezone): static
diff --git a/src/Symfony/Component/Clock/Tests/MockClockTest.php b/src/Symfony/Component/Clock/Tests/MockClockTest.php
index be1f8316055f8..caafcbdb42608 100644
--- a/src/Symfony/Component/Clock/Tests/MockClockTest.php
+++ b/src/Symfony/Component/Clock/Tests/MockClockTest.php
@@ -55,11 +55,11 @@ public function testNow()
 
     public function testSleep()
     {
-        $clock = new MockClock((new \DateTimeImmutable('@123.456'))->setTimezone(new \DateTimeZone('UTC')));
+        $clock = new MockClock((new \DateTimeImmutable('2112-09-17 23:53:00.999Z'))->setTimezone(new \DateTimeZone('UTC')));
         $tz = $clock->now()->getTimezone()->getName();
 
-        $clock->sleep(4.999);
-        $this->assertSame('128.455000', $clock->now()->format('U.u'));
+        $clock->sleep(2.002001);
+        $this->assertSame('2112-09-17 23:53:03.001001', $clock->now()->format('Y-m-d H:i:s.u'));
         $this->assertSame($tz, $clock->now()->getTimezone()->getName());
     }