diff --git a/glance/db/__init__.py b/glance/db/__init__.py
index 50e3e2ff3f..72cccae3de 100644
--- a/glance/db/__init__.py
+++ b/glance/db/__init__.py
@@ -253,7 +253,8 @@ class ImageRepo(object):
 
     def add(self, image):
         image_values = self._format_image_to_db(image)
-        if image_values['size'] > CONF.image_size_cap:
+        if (image_values['size'] is not None
+           and image_values['size'] > CONF.image_size_cap):
             raise exception.ImageSizeLimitExceeded
         # the updated_at value is not set in the _format_image_to_db
         # function since it is specific to image create
@@ -266,7 +267,8 @@ class ImageRepo(object):
 
     def save(self, image, from_state=None):
         image_values = self._format_image_to_db(image)
-        if image_values['size'] > CONF.image_size_cap:
+        if (image_values['size'] is not None
+           and image_values['size'] > CONF.image_size_cap):
             raise exception.ImageSizeLimitExceeded
         try:
             new_values = self.db_api.image_update(self.context,
diff --git a/glance/db/simple/api.py b/glance/db/simple/api.py
index bfb5066955..f9852912d5 100644
--- a/glance/db/simple/api.py
+++ b/glance/db/simple/api.py
@@ -145,7 +145,7 @@ def _image_member_format(image_id, tenant_id, can_share, status='pending'):
 
 def _pop_task_info_values(values):
     task_info_values = {}
-    for k, v in values.items():
+    for k, v in list(values.items()):
         if k in ['input', 'result', 'message']:
             values.pop(k)
             task_info_values[k] = v
@@ -373,7 +373,7 @@ def _sort_images(images, sort_key, sort_dir):
         raise exception.Invalid(message='Number of sort dirs does not match '
                                         'the number of sort keys')
 
-    for key, dir in reversed(zip(sort_key, sort_dir)):
+    for key, dir in reversed(list(zip(sort_key, sort_dir))):
         reverse = dir == 'desc'
         images.sort(key=itemgetter(key), reverse=reverse)
 
@@ -489,7 +489,7 @@ def image_member_count(context, image_id):
         raise exception.Invalid(msg)
 
     members = DATA['members']
-    return len(filter(lambda x: x['image_id'] == image_id, members))
+    return len([x for x in members if x['image_id'] == image_id])
 
 
 @log_call
diff --git a/tox.ini b/tox.ini
index 1272633600..cba2b4e0e6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -33,6 +33,7 @@ commands =
     glance.tests.unit.test_cache_middleware \
     glance.tests.unit.test_context \
     glance.tests.unit.test_context_middleware \
+    glance.tests.unit.test_db \
     glance.tests.unit.test_db_metadef \
     glance.tests.unit.test_domain \
     glance.tests.unit.test_domain_proxy \
@@ -44,6 +45,7 @@ commands =
     glance.tests.unit.test_notifier \
     glance.tests.unit.test_opts \
     glance.tests.unit.test_policy \
+    glance.tests.unit.test_quota \
     glance.tests.unit.test_schema \
     glance.tests.unit.test_scrubber \
     glance.tests.unit.test_store_artifact \