diff --git a/pySim/exceptions.py b/pySim/exceptions.py
index 2ffe5f97..4fb8f72a 100644
--- a/pySim/exceptions.py
+++ b/pySim/exceptions.py
@@ -39,7 +39,7 @@ class SwMatchError(Exception):
 		self.rs = rs
 	def __str__(self):
 		if self.rs:
-			r = self.rs.interpret_sw(sw_actual)
+			r = self.rs.interpret_sw(self.sw_actual)
 			if r:
 				return "SW match failed! Expected %s and got %s: %s - %s" % (self.sw_expected, self.sw_actual, r[0], r[1])
 		return "SW match failed! Expected %s and got %s." % (self.sw_expected, self.sw_actual)