diff --git a/pySim/cards.py b/pySim/cards.py
index 4dee0d8d..e294f9ac 100644
--- a/pySim/cards.py
+++ b/pySim/cards.py
@@ -338,7 +338,7 @@ class GrcardSim(Card):
 
 		# Authenticate using ADM PIN 5
 		if p['pin_adm']:
-			pin = p['pin_adm']
+			pin = h2b(p['pin_adm'])
 		else:
 			pin = h2b("4444444444444444")
 		self._scc.verify_chv(5, pin)