diff --git a/src/urh/controller/dialogs/SimulatorDialog.py b/src/urh/controller/dialogs/SimulatorDialog.py
index 4cb6cbd36..24bf47864 100644
--- a/src/urh/controller/dialogs/SimulatorDialog.py
+++ b/src/urh/controller/dialogs/SimulatorDialog.py
@@ -230,7 +230,7 @@ def update_transcript_view(self):
     def closeEvent(self, event: QCloseEvent):
         self.timer.stop()
         self.simulator.stop()
-        time.sleep(0.1)
+
         self.simulator.cleanup()
 
         self.emit_editing_finished_signals()
diff --git a/src/urh/simulator/Simulator.py b/src/urh/simulator/Simulator.py
index f7c206b67..d470e4672 100644
--- a/src/urh/simulator/Simulator.py
+++ b/src/urh/simulator/Simulator.py
@@ -118,6 +118,7 @@ def stop(self, msg=""):
             self.log_message("Stop simulation" + (" ({})".format(msg.strip()) if msg else ""))
             self.is_simulating = False
             self.do_restart = False
+            self.simulation_thread.join(2.5)
 
         # stop devices
         if self.sniffer: