diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index d9f14fa..249b5f6 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1188,11 +1188,11 @@
             # calls communicate again.
             if self.stdout is not None:
                 self.stdout_thread.join(self._remaining_time(endtime))
-                if self.stdout_thread.isAlive():
+                if self.stdout_thread.is_alive():
                     raise TimeoutExpired(self.args, orig_timeout)
             if self.stderr is not None:
                 self.stderr_thread.join(self._remaining_time(endtime))
-                if self.stderr_thread.isAlive():
+                if self.stderr_thread.is_alive():
                     raise TimeoutExpired(self.args, orig_timeout)
 
             # Collect the output from and close both pipes, now that we know