diff --git a/Lib/mailcap.py b/Lib/mailcap.py
index 4ae13d7..99f4958 100644
--- a/Lib/mailcap.py
+++ b/Lib/mailcap.py
@@ -33,10 +33,10 @@
 
 def listmailcapfiles():
     """Return a list of all mailcap files found on the system."""
-    # XXX Actually, this is Unix-specific
+    # This is mostly a Unix thing, but we use the OS path separator anyway
     if 'MAILCAPS' in os.environ:
-        str = os.environ['MAILCAPS']
-        mailcaps = str.split(':')
+        pathstr = os.environ['MAILCAPS']
+        mailcaps = pathstr.split(os.pathsep)
     else:
         if 'HOME' in os.environ:
             home = os.environ['HOME']