diff --git a/Lib/httplib.py b/Lib/httplib.py
index 4bad463..ce819eb 100644
--- a/Lib/httplib.py
+++ b/Lib/httplib.py
@@ -347,7 +347,10 @@
         if port is None:
             i = host.find(':')
             if i >= 0:
-                port = int(host[i+1:])
+                try:
+                    port = int(host[i+1:])
+                except ValueError:
+                    raise InvalidURL, "nonnumeric port: '%s'"%host[i+1:]
                 host = host[:i]
             else:
                 port = self.default_port
@@ -808,6 +811,9 @@
 class NotConnected(HTTPException):
     pass
 
+class InvalidURL(HTTPException):
+    pass
+
 class UnknownProtocol(HTTPException):
     def __init__(self, version):
         self.version = version