diff --git a/qasync/__init__.py b/qasync/__init__.py
index 3363e97..f797c85 100644
--- a/qasync/__init__.py
+++ b/qasync/__init__.py
@@ -149,9 +149,15 @@ def run(self):
                 else:
                     self._logger.debug("Setting Future result: %s", r)
                     future.set_result(r)
+                finally:
+                    # Release potential reference
+                    r = None  # noqa
             else:
                 self._logger.debug("Future was canceled")
 
+            # Delete references
+            del command, future, callback, args, kwargs
+
         self._logger.debug("Thread #%s stopped", self.__num)
 
     def wait(self):