diff -Naur a/src/controller_slot.cpp b/src/controller_slot.cpp
--- a/src/controller_slot.cpp	2015-11-09 10:19:35.000000000 -0000
+++ b/src/controller_slot.cpp	2021-08-02 13:05:48.647684177 -0000
@@ -69,7 +69,7 @@
 bool
 ControllerSlot::is_connected() const
 {
-  return m_thread;
+  return m_thread.get();
 }
 
 /* EOF */