diff --git a/pwrtls.py b/pwrtls.py
index aa4006b..9ab9238 100644
--- a/pwrtls.py
+++ b/pwrtls.py
@@ -173,7 +173,9 @@ def do_handshake(self):
 
 		# receive verification message for authenticating the short-term key
 		data = self._recv_frame()
-		opened = nacl.crypto_box_open(data, snonce(3), self.remote_shortpub, self.shortpriv)
+		try: opened = nacl.crypto_box_open(data, snonce(3), self.remote_shortpub, self.shortpriv)
+		except ValueError:
+			raise pwrtls_exception('Could not open client_verify message.')
 		self.remote_longpub, vbox, vnonce, pskv, cav = from_bson(opened, 'lpub', 'v', 'vn', 'pskv', 'cav')
 
 		# check verifybox