diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py
index 40abeda816963b..00de9d0ac921d2 100644
--- a/Lib/test/_test_multiprocessing.py
+++ b/Lib/test/_test_multiprocessing.py
@@ -625,10 +625,10 @@ def _kill_process(self, meth, target=None):
             # On the Gentoo buildbot waitpid() often seems to block forever.
             # We use alarm() to interrupt it if it blocks for too long.
             def handler(*args):
-                raise RuntimeError('join took too long: %s' % p)
+                raise RuntimeError(f'join took longer than {timeout} seconds: {p}')
             old_handler = signal.signal(signal.SIGALRM, handler)
             try:
-                signal.alarm(10)
+                signal.alarm(int(timeout))
                 self.assertEqual(join(), None)
             finally:
                 signal.alarm(0)