diff --git a/owrx/cpu.py b/owrx/cpu.py
index 6b2b82c..bff3f42 100644
--- a/owrx/cpu.py
+++ b/owrx/cpu.py
@@ -23,6 +23,7 @@ class CpuUsageThread(threading.Thread):
         self.last_idletime = 0
         self.endEvent = threading.Event()
         super().__init__()
+        self.start()
 
     def run(self):
         logger.debug("cpu usage thread starting up")
@@ -59,8 +60,6 @@ class CpuUsageThread(threading.Thread):
 
     def add_client(self, c):
         self.clients.append(c)
-        if not self.is_alive():
-            self.start()
 
     def remove_client(self, c):
         try:
@@ -71,6 +70,7 @@ class CpuUsageThread(threading.Thread):
             self.shutdown()
 
     def shutdown(self):
-        CpuUsageThread.sharedInstance = None
+        with CpuUsageThread.creationLock:
+            CpuUsageThread.sharedInstance = None
         self.doRun = False
         self.endEvent.set()