diff --git a/earwigbot/bot.py b/earwigbot/bot.py
index d67e864..df59950 100644
--- a/earwigbot/bot.py
+++ b/earwigbot/bot.py
@@ -154,7 +154,7 @@ class Bot(object):
                 tasks.append(thread.name)
         if tasks:
             log = "The following commands or tasks will be killed: {0}"
-            self.logger.warn(log.format(" ".join(tasks)))
+            self.logger.warn(log.format(", ".join(tasks)))
 
     @property
     def is_running(self):