diff --git a/src/Symfony/Component/RateLimiter/Policy/SlidingWindow.php b/src/Symfony/Component/RateLimiter/Policy/SlidingWindow.php
index cb27197f9ee87..7bc85e522613b 100644
--- a/src/Symfony/Component/RateLimiter/Policy/SlidingWindow.php
+++ b/src/Symfony/Component/RateLimiter/Policy/SlidingWindow.php
@@ -122,6 +122,6 @@ public function getHitCount(): int
 
     public function getRetryAfter(): \DateTimeImmutable
     {
-        return \DateTimeImmutable::createFromFormat('U.u', $this->windowEndAt);
+        return \DateTimeImmutable::createFromFormat('U.u', sprintf('%.6F', $this->windowEndAt));
     }
 }
diff --git a/src/Symfony/Component/RateLimiter/Tests/Policy/SlidingWindowTest.php b/src/Symfony/Component/RateLimiter/Tests/Policy/SlidingWindowTest.php
index f81784706c185..df1d01499679b 100644
--- a/src/Symfony/Component/RateLimiter/Tests/Policy/SlidingWindowTest.php
+++ b/src/Symfony/Component/RateLimiter/Tests/Policy/SlidingWindowTest.php
@@ -102,4 +102,13 @@ public function testGetRetryAfterUsesMicrotime()
         // should be 500ms left (10 - 9.5)
         $this->assertEqualsWithDelta(0.5, $window->getRetryAfter()->format('U.u') - microtime(true), 0.2);
     }
+
+    public function testCreateAtExactTime()
+    {
+        ClockMock::register(SlidingWindow::class);
+        ClockMock::withClockMock(1234567890.000000);
+        $window = new SlidingWindow('foo', 10);
+        $window->getRetryAfter();
+        $this->assertEquals('1234567900.000000', $window->getRetryAfter()->format('U.u'));
+    }
 }