diff --git a/archivemail.py b/archivemail.py
index ed044e8..a0263a4 100755
--- a/archivemail.py
+++ b/archivemail.py
@@ -685,7 +685,7 @@ def guess_return_path(message):
     assert(message)
 
     for header in ('Return-path', 'From'):
-        address_header = message.get('header')
+        address_header = message.get(header)
         if address_header:
             (name, address) = rfc822.parseaddr(address_header)
             if address: