diff --git a/escpos/printer.py b/escpos/printer.py
index 4b2088b..640c3f4 100644
--- a/escpos/printer.py
+++ b/escpos/printer.py
@@ -31,7 +31,7 @@ class Usb(Escpos):
         self.interface = interface
         self.in_ep     = in_ep
         self.out_ep    = out_ep
-	self.open()
+        self.open()
 
 
     def open(self):