diff --git a/hgext/largefiles/lfcommands.py b/hgext/largefiles/lfcommands.py
--- a/hgext/largefiles/lfcommands.py
+++ b/hgext/largefiles/lfcommands.py
@@ -464,7 +464,7 @@ def _updatelfile(repo, lfdirstate, lfile
 
 cmdtable = {
     'lfconvert': (lfconvert,
-                  [('s', 'size', 0, 'All files over this size (in megabytes) '
+                  [('s', 'size', '', 'All files over this size (in megabytes) '
                   'will be considered largefiles. This can also be specified '
                   'in your hgrc as [largefiles].size.'),
                   ('','tonormal',False,
diff --git a/hgext/largefiles/lfutil.py b/hgext/largefiles/lfutil.py
--- a/hgext/largefiles/lfutil.py
+++ b/hgext/largefiles/lfutil.py
@@ -64,9 +64,9 @@ def getminsize(ui, assumelfiles, opt, de
         lfsize = ui.config(longname, 'size', default=default)
     if lfsize:
         try:
-            lfsize = int(lfsize)
+            lfsize = float(lfsize)
         except ValueError:
-            raise util.Abort(_('largefiles: size must be an integer, was %s\n')
+            raise util.Abort(_('largefiles: size must be number (not %s)\n')
                              % lfsize)
     if lfsize is None:
         raise util.Abort(_('minimum size for largefiles must be specified'))