diff --git a/salt/ext/tornado/concurrent.py b/salt/ext/tornado/concurrent.py
index bea09ba125..011808ed27 100644
--- a/salt/ext/tornado/concurrent.py
+++ b/salt/ext/tornado/concurrent.py
@@ -330,12 +330,13 @@ def _check_done(self):
 
     def _set_done(self):
         self._done = True
-        for cb in self._callbacks:
-            try:
-                cb(self)
-            except Exception:
-                app_log.exception("Exception in callback %r for %r", cb, self)
-        self._callbacks = None
+        if self._callbacks:
+            for cb in self._callbacks:
+                try:
+                    cb(self)
+                except Exception:
+                    app_log.exception("Exception in callback %r for %r", cb, self)
+            self._callbacks = None
 
     # On Python 3.3 or older, objects with a destructor part of a reference
     # cycle are never destroyed. It's no longer the case on Python 3.4 thanks to