diff --git a/miniuri.py b/miniuri.py
index ecd76a0..1c8d445 100644
--- a/miniuri.py
+++ b/miniuri.py
@@ -76,19 +76,22 @@ class Uri( object ):
     @property
     def userinfo( self ):
         """return username:password"""
-        return self.username + ':' + self.password
+        if self.username and self.password: 
+            return self.username + ':' + self.password
+        if self.username: return self.username
+        else: return None
 
     @userinfo.setter
     def userinfo( self, info ):
         """set username and password"""
         self.username, self.password = info, None 
-        if ':' in self.username: 
-            self.username, self.password = self.username.split( ':' )
+        if ':' in info:
+            self.username, self.password = info.split( ':' )
 
     @property
     def extension( self ):
         """return extension"""
-        if '.' in self.filename: return self.filename.split('.')[1]
+        if '.' in self.filename: return self.filename.split('.')[-1]
         else: return None 
 
     @property