diff --git a/pySim/exceptions.py b/pySim/exceptions.py
index c0cf1e7..5d30f76 100644
--- a/pySim/exceptions.py
+++ b/pySim/exceptions.py
@@ -5,6 +5,7 @@
 
 #
 # Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
+# Copyright (C) 2021 Harald Welte <laforge@osmocom.org>
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -36,3 +37,12 @@
 
 class ReaderError(Exception):
 	pass
+
+class SwMatchError(Exception):
+	"""Raised when an operation specifies an expected SW but the actual SW from
+	   the card doesn't match."""
+	def __init__(self, sw_actual, sw_expected):
+		self.sw_actual = sw_actual
+		self.sw_expected = sw_expected
+	def __str__(self):
+		return "SW match failed! Expected %s and got %s." % (self.sw_expected, self.sw_actual)
diff --git a/pySim/transport/__init__.py b/pySim/transport/__init__.py
index 8e009ee..00c7bd9 100644
--- a/pySim/transport/__init__.py
+++ b/pySim/transport/__init__.py
@@ -3,6 +3,8 @@
 """ pySim: PCSC reader transport link base
 """
 
+from pySim.exceptions import *
+
 #
 # Copyright (C) 2009-2010  Sylvain Munaut <tnt@246tNt.com>
 #
@@ -100,5 +102,5 @@
 				sw_masked = sw_masked + rv[1][i].lower()
 
 		if sw.lower() != sw_masked:
-			raise RuntimeError("SW match failed! Expected %s and got %s." % (sw.lower(), rv[1]))
+			raise SwMatchError(rv[1], sw.lower())
 		return rv