diff --git a/api/lib/LoginThrottle.php b/api/lib/LoginThrottle.php
index e1952350..fce40235 100644
--- a/api/lib/LoginThrottle.php
+++ b/api/lib/LoginThrottle.php
@@ -78,6 +78,9 @@ final class LoginThrottle
     /** Removes the files of addresses whose failures are all too old to matter. */
     public function prune(): int
     {
+        // PHP keeps what it learned of a file for the rest of the request; a time read earlier
+        // would keep a file that has gone stale since, or drop one written since.
+        clearstatcache();
         $removed = 0;
         foreach (glob($this->dir . '/*.json') ?: [] as $path) {
             if ((int) filemtime($path) < $this->now() - 2 * self::WINDOW_SECONDS && unlink($path)) {