diff --git a/expiringdict/__init__.py b/expiringdict/__init__.py
index ad27546..b869190 100755
--- a/expiringdict/__init__.py
+++ b/expiringdict/__init__.py
@@ -58,14 +58,17 @@ def __init__(self, max_len, max_age_seconds, items=None):
     def __len__(self):
         with self.lock:
             current_key = iter(self)
+            keys_to_del = []
             for k in current_key:
                 item = OrderedDict.__getitem__(self, k)
                 time_added = item[1]
                 item_age = time.time() - time_added
                 if item_age > self.max_age:
-                    del self[k]
+                    keys_to_del.append(k)
                 else:
                     break
+            for k in keys_to_del:
+                del self[k]
 
         return super(ExpiringDict, self).__len__()
 
diff --git a/tests/expiringdict_test.py b/tests/expiringdict_test.py
index bf17a39..6663981 100644
--- a/tests/expiringdict_test.py
+++ b/tests/expiringdict_test.py
@@ -65,7 +65,7 @@ def test_repr():
     d['a'] = 'x'
     eq_(str(d), "ExpiringDict([('a', 'x')])")
     sleep(0.01)
-    eq_(str(d), "ExpiringDict()")
+    eq_(str(d), "ExpiringDict([])")
 
 
 def test_iter():