diff --git a/Lib/macurl2path.py b/Lib/macurl2path.py
index 7d273bc..4c43d21 100644
--- a/Lib/macurl2path.py
+++ b/Lib/macurl2path.py
@@ -13,6 +13,11 @@
     tp = urllib.splittype(pathname)[0]
     if tp and tp <> 'file':
         raise RuntimeError, 'Cannot convert non-local URL to pathname'
+    # Turn starting /// into /, an empty hostname means current host
+    if pathname[:3] == '///':
+    	pathname = pathname[2:]
+    elif pathname[:2] == '//':
+        raise RuntimeError, 'Cannot convert non-local URL to pathname'
     components = string.split(pathname, '/')
     # Remove . and embedded ..
     i = 0