diff --git a/stressor/run_manager.py b/stressor/run_manager.py
index a74498a..bd7682d 100644
--- a/stressor/run_manager.py
+++ b/stressor/run_manager.py
@@ -349,7 +349,7 @@ def run_in_threads(self, user_list, context):
             sess = SessionManager(self, context, name, user)
             self.session_list.append(sess)
             t = threading.Thread(name=name, target=self._run_one, args=[sess])
-            t.setDaemon(True)  # Required to make Ctrl-C work
+            t.daemon = True  # Required to make Ctrl-C work
             thread_list.append(t)
 
         logger.info(f"Starting {len(thread_list)} session workers...")