diff --git a/pySim/transport/serial.py b/pySim/transport/serial.py
index b841b3e..7785b4a 100644
--- a/pySim/transport/serial.py
+++ b/pySim/transport/serial.py
@@ -52,7 +52,8 @@
 		self._atr = None
 
 	def __del__(self):
-		self._sl.close()
+		if (hasattr(self, "_sl")):
+			self._sl.close()
 
 	def wait_for_card(self, timeout=None, newcardonly=False):
 		# Direct try