diff --git a/untls_proxy.py b/untls_proxy.py
index ad5441b..ff7ee64 100755
--- a/untls_proxy.py
+++ b/untls_proxy.py
@@ -245,7 +245,7 @@ def proxy(sock, host):
 	elif b':' not in remote_host:
 		port = None
 	else:
-		remote_host, port = remote_host.rsplit(b':')
+		remote_host, port = remote_host.rsplit(b':', 1)
 		try:
 			port = int(port)
 			if port < 1 or port > 0xffff: raise ValueError