diff --git a/test/php/Handler.php b/test/php/Handler.php
index a03554c..670720f 100644
--- a/test/php/Handler.php
+++ b/test/php/Handler.php
@@ -170,6 +170,8 @@
 
     public function testOneway($secondsToSleep)
     {
+        // Keep the oneway test quick so the cross-test matrix measures fire-and-forget behavior,
+        // not a full second of handler blocking in the single-threaded PHP test server.
         usleep($secondsToSleep * 300000);
     }
 }