diff --git a/tailbone/views/master.py b/tailbone/views/master.py
index 15734212..ea911bd0 100644
--- a/tailbone/views/master.py
+++ b/tailbone/views/master.py
@@ -3772,16 +3772,17 @@ class MasterView(View):
             return tags.link_to(content, url)
         return content
 
-    def readable_size(self, path):
+    def readable_size(self, path, size=None):
         # TODO: this was shamelessly copied from FormAlchemy ...
-        length = self.get_size(path)
-        if length == 0:
+        if size is None:
+            size = self.get_size(path)
+        if size == 0:
             return '0 KB'
-        if length <= 1024:
+        if size <= 1024:
             return '1 KB'
-        if length > 1048576:
-            return '%0.02f MB' % (length / 1048576.0)
-        return '%0.02f KB' % (length / 1024.0)
+        if size > 1048576:
+            return '%0.02f MB' % (size / 1048576.0)
+        return '%0.02f KB' % (size / 1024.0)
 
     def get_size(self, path):
         try: