diff --git a/Lib/urlopen.py b/Lib/urlopen.py
index 0f3c33a..47f0f20 100755
--- a/Lib/urlopen.py
+++ b/Lib/urlopen.py
@@ -169,6 +169,7 @@
 	# Use FTP protocol
 	def open_ftp(self, url):
 		host, file = splithost(url)
+		if not host: raise IOError, ('ftp error', 'no host given')
 		host, port = splitport(host)
 		host = socket.gethostbyname(host)
 		if not port: