diff --git a/progress.py b/progress.py
index 2ace701..d948654 100644
--- a/progress.py
+++ b/progress.py
@@ -21,13 +21,14 @@
 _NOT_TTY = not os.isatty(2)
 
 class Progress(object):
-  def __init__(self, title, total=0):
+  def __init__(self, title, total=0, units=''):
     self._title = title
     self._total = total
     self._done = 0
     self._lastp = -1
     self._start = time()
     self._show = False
+    self._units = units
 
   def update(self, inc=1):
     self._done += inc
@@ -51,11 +52,11 @@
 
       if self._lastp != p:
         self._lastp = p
-        sys.stderr.write('\r%s: %3d%% (%d/%d)  ' % (
+        sys.stderr.write('\r%s: %3d%% (%d%s/%d%s)  ' % (
           self._title,
           p,
-          self._done,
-          self._total))
+          self._done, self._units,
+          self._total, self._units))
         sys.stderr.flush()
 
   def end(self):
@@ -69,9 +70,9 @@
       sys.stderr.flush()
     else:
       p = (100 * self._done) / self._total
-      sys.stderr.write('\r%s: %3d%% (%d/%d), done.  \n' % (
+      sys.stderr.write('\r%s: %3d%% (%d%s/%d%s), done.  \n' % (
         self._title,
         p,
-        self._done,
-        self._total))
+        self._done, self._units,
+        self._total, self._units))
       sys.stderr.flush()