diff --git a/CHANGES.rst b/CHANGES.rst
index 5ab00d6..ffe9883 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,6 +4,12 @@ Changelog
 Here you can see the full list of changes between each SQLAlchemy-Utils release.
 
 
+0.12.4 (2013-06-01)
+^^^^^^^^^^^^^^^^^^^
+
+- Fixed ProxyDict contains method
+
+
 0.12.3 (2013-05-30)
 ^^^^^^^^^^^^^^^^^^^
 
diff --git a/setup.py b/setup.py
index f6735ec..c14e256 100644
--- a/setup.py
+++ b/setup.py
@@ -24,7 +24,7 @@ class PyTest(Command):
 
 setup(
     name='SQLAlchemy-Utils',
-    version='0.12.3',
+    version='0.12.4',
     url='https://github.com/kvesteri/sqlalchemy-utils',
     license='BSD',
     author='Konsta Vesterinen',
diff --git a/sqlalchemy_utils/proxy_dict.py b/sqlalchemy_utils/proxy_dict.py
index 6b33fef..df1bade 100644
--- a/sqlalchemy_utils/proxy_dict.py
+++ b/sqlalchemy_utils/proxy_dict.py
@@ -19,31 +19,33 @@ class ProxyDict(object):
 
     def __contains__(self, key):
         try:
-            return key in self.cache or self[key]
+            return key in self.cache or self.fetch(key) is not None
         except KeyError:
             return False
 
+    def has_key(self, key):
+        return self.__contains__(key)
+
     def fetch(self, key):
-        return self.collection.filter_by(**{self.key_name: key}).first()
+        session = sa.orm.object_session(self.parent)
+        if session and sa.orm.util.has_identity(self.parent):
+            return self.collection.filter_by(**{self.key_name: key}).first()
 
     def create_new_instance(self, key):
         value = self.child_class(**{self.key_name: key})
         self.collection.append(value)
+        self.cache[key] = value
         return value
 
     def __getitem__(self, key):
         if key in self.cache:
             return self.cache[key]
 
-        session = sa.orm.object_session(self.parent)
-        if not session or not sa.orm.util.has_identity(self.parent):
-            value = self.create_new_instance(key)
-        else:
-            value = self.fetch(key)
-            if not value:
-                value = self.create_new_instance(key)
-        self.cache[key] = value
-        return value
+        value = self.fetch(key)
+        if value:
+            return value
+
+        return self.create_new_instance(key)
 
     def __setitem__(self, key, value):
         try:
diff --git a/tests/test_proxy_dict.py b/tests/test_proxy_dict.py
index fd60aee..13ebcd9 100644
--- a/tests/test_proxy_dict.py
+++ b/tests/test_proxy_dict.py
@@ -79,6 +79,12 @@ class TestProxyDict(TestCase):
         )
         article.translations['en']
 
+    def test_contains(self):
+        article = self.Article()
+        assert 'en' not in article.translations
+        # does not auto-append new translation
+        assert 'en' not in article.translations
+
     def test_committing_session_empties_proxy_dict_cache(self):
         article = self.Article()
         (