diff --git a/mercurial/archival.py b/mercurial/archival.py
--- a/mercurial/archival.py
+++ b/mercurial/archival.py
@@ -35,6 +35,20 @@ def tidyprefix(dest, prefix, suffixes):
         raise util.Abort(_('archive prefix contains illegal components'))
     return prefix
 
+exts = {
+    'tar': ['.tar'],
+    'tbz2': ['.tbz2', '.tar.bz2'],
+    'tgz': ['.tgz', '.tar.gz'],
+    'zip': ['.zip'],
+    }
+
+def guesskind(dest):
+    for kind, extensions in exts.iteritems():
+        if util.any(dest.endswith(ext) for ext in extensions):
+            return kind
+    return None
+
+
 class tarit(object):
     '''write archive to tar file or stream.  can write uncompressed,
     or compress with gzip or bzip2.'''
diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -196,20 +196,7 @@ def archive(ui, repo, dest, **opts):
     if os.path.realpath(dest) == repo.root:
         raise util.Abort(_('repository root cannot be destination'))
 
-    def guess_type():
-        exttypes = {
-            'tar': ['.tar'],
-            'tbz2': ['.tbz2', '.tar.bz2'],
-            'tgz': ['.tgz', '.tar.gz'],
-            'zip': ['.zip'],
-        }
-
-        for type, extensions in exttypes.items():
-            if util.any(dest.endswith(ext) for ext in extensions):
-                return type
-        return None
-
-    kind = opts.get('type') or guess_type() or 'files'
+    kind = opts.get('type') or archival.guesskind(dest) or 'files'
     prefix = opts.get('prefix')
 
     if dest == '-':