diff --git a/localtunnel/cli.py b/localtunnel/cli.py
index 70469ed..16b08ac 100644
--- a/localtunnel/cli.py
+++ b/localtunnel/cli.py
@@ -9,19 +9,24 @@ This module provides the command-line interface for Localtunnel.
 import sys
 
 import clint
+from clint.arguments import _expand_path as expand_path
 
-USAGE = """
+USAGE = '''
 Usage: localtunnel [options] <localport>
     -k, --key FILE                   upload a public key for authentication
     -h, --help                       show this help
-""".lstrip()
+'''.lstrip()
 
+PORT_ERROR = 'Invalid port number.'
 
 def display_usage():
     """Displays localtunnel usage."""
-
     print USAGE
 
+def display_port_error():
+    print PORT_ERROR
+
+
 def main():
     """Main localtunnel dispatch."""
 
@@ -31,6 +36,8 @@ def main():
 
     elif ('-k', '--key') in clint.args:
         print 'importing key'
+        # print clint.args.files
+        print expand_path('~/ssh/*.pub')
         sys.exit()
 
     elif not len(clint.args.not_flags):
@@ -39,5 +46,11 @@ def main():
 
     port = clint.args.not_flags.pop(0)
 
+    try:
+        int(port)
+    except ValueError:
+        display_port_error()
+        sys.exit(1)
+
 if __name__ == '__main__':
     main()
\ No newline at end of file