diff --git a/addons/hw_escpos/controllers/main.py b/addons/hw_escpos/controllers/main.py
index 58c02ebf59f..886b3a96431 100644
--- a/addons/hw_escpos/controllers/main.py
+++ b/addons/hw_escpos/controllers/main.py
@@ -51,11 +51,10 @@ class EscposDriver(Thread):
         return connected
 
     def lockedstart(self):
-        self.lock.acquire()
-        if not self.isAlive():
-            self.daemon = True
-            self.start()
-        self.lock.release()
+        with self.lock:
+            if not self.isAlive():
+                self.daemon = True
+                self.start()
     
     def get_escpos_printer(self):
         try:
diff --git a/addons/hw_scanner/controllers/main.py b/addons/hw_scanner/controllers/main.py
index 8fbdae62db6..5c9cb50e906 100644
--- a/addons/hw_scanner/controllers/main.py
+++ b/addons/hw_scanner/controllers/main.py
@@ -88,10 +88,10 @@ class Scanner(Thread):
         }
 
     def lockedstart(self):
-        self.lock.acquire()
-        if not self.isAlive():
-            self.start()
-        self.lock.release()
+        with self.lock:
+            if not self.isAlive():
+                self.daemon = True
+                self.start()
 
     def set_status(self, status, message = None):
         if status == self.status['status']: