diff --git a/oec/__main__.py b/oec/__main__.py
index 5b3054d..5125e48 100644
--- a/oec/__main__.py
+++ b/oec/__main__.py
@@ -86,6 +86,28 @@ def _create_session(args, device):
 
     raise ValueError('Unsupported emulator')
 
+def parse_tn3270_host_args(args, parser):
+    elements = args.host.rsplit(':', 1)
+
+    host = elements[0]
+    port = None
+
+    if len(elements) > 1:
+        try:
+            port = int(elements[1])
+        except ValueError:
+            parser.error(f'argument host: invalid port value: {elements[1]}')
+
+    if args.port is not None:
+        if port is None:
+            port = args.port
+
+            logger.info('The port argument is deprecated and will be removed in the future, use host:port instead.')
+        else:
+            logger.warning('The port argument is deprecated and will be removed in the future, port from host:port is being used.')
+
+    return (host, port if port is not None else 23)
+
 def _signal_handler(number, frame):
     global CONTROLLER
 
@@ -104,16 +126,17 @@ def main():
 
     parser = argparse.ArgumentParser(description='IBM 3270 terminal controller')
 
-    parser.add_argument('serial_port', help='Serial port')
+    parser.add_argument('serial_port', help='serial port')
 
     subparsers = parser.add_subparsers(dest='emulator', required=True,
-                                       description='Emulator')
+                                       description='emulator')
 
     tn3270_parser = subparsers.add_parser('tn3270', description='TN3270 emulator',
                                           help='TN3270 emulator')
 
-    tn3270_parser.add_argument('host', help='Hostname')
-    tn3270_parser.add_argument('port', nargs='?', default=23, type=int)
+    tn3270_parser.add_argument('host', metavar='host[:port]',
+                               help='host and optional port')
+    tn3270_parser.add_argument('port', nargs='?', type=int, help=argparse.SUPPRESS)
 
     tn3270_parser.add_argument('--codepage', metavar='encoding', default='ibm037',
                                dest='character_encoding', type=_get_character_encoding)
@@ -122,12 +145,15 @@ def main():
         vt100_parser = subparsers.add_parser('vt100', description='VT100 emulator',
                                              help='VT100 emulator')
 
-        vt100_parser.add_argument('command', help='Host process')
+        vt100_parser.add_argument('command', help='host process')
         vt100_parser.add_argument('command_args', nargs=argparse.REMAINDER,
-                                  help='Host process arguments')
+                                  help='host process arguments')
 
     args = parser.parse_args()
 
+    if args.emulator == 'tn3270':
+        (args.host, args.port) = parse_tn3270_host_args(args, parser)
+
     create_device = lambda interface, device_address, poll_response: _create_device(args, interface, device_address, poll_response)
     create_session = lambda device: _create_session(args, device)