diff --git a/rocksock.py b/rocksock.py
index 1edac4c..c7c2ebf 100644
--- a/rocksock.py
+++ b/rocksock.py
@@ -111,7 +111,7 @@ class RocksockException(Exception):
 			if self.error == RS_E_SSL_GENERIC and self.failedproxy != None:
 				msg += ': ' + self.failedproxy #failedproxy is repurposed for SSL exceptions
 		else: #RS_ET_OWN
-			msg = errordict[self.error]
+			msg = errordict[self.error] + " (proxy %d)"%self.failedproxy
 		return msg
 
 
@@ -127,6 +127,8 @@ class RocksockProxy():
 			    'socks5' : RS_PT_SOCKS5,
 			    'http'   : RS_PT_HTTP }
 		self.type = typemap[type] if type in typemap else type
+		if not self.type in [RS_PT_NONE, RS_PT_SOCKS4, RS_PT_SOCKS5, RS_PT_HTTP]:
+			raise ValueError('Invalid proxy type')
 		self.username = username
 		self.password = password
 		self.hostinfo = RocksockHostinfo(host, port)