diff --git a/package_control/clients/github_client.py b/package_control/clients/github_client.py
index cc25e082..a6f0f30f 100644
--- a/package_control/clients/github_client.py
+++ b/package_control/clients/github_client.py
@@ -187,7 +187,7 @@ def _get_releases(user_repo, tag_prefix=None, page_size=1000):
             version, tag, tag_url = release
 
             if is_client:
-                timestamp = 0
+                timestamp = '1970-01-01 00:00:00'
             else:
                 tag_info = self.fetch_json(tag_url)
                 timestamp = tag_info['commit']['committer']['date'][0:19].replace('T', ' ')
diff --git a/package_control/providers/repository_provider.py b/package_control/providers/repository_provider.py
index c6fabf01..565a453b 100644
--- a/package_control/providers/repository_provider.py
+++ b/package_control/providers/repository_provider.py
@@ -787,8 +787,9 @@ def has_broken_release():
                 # Extract a date from the newest release
                 date = '1970-01-01 00:00:00'
                 for release in info['releases']:
-                    if 'date' in release and release['date'] > date:
-                        date = release['date']
+                    release_date = release.get('date')
+                    if release_date and isinstance(release_date, str) and release_date > date:
+                        date = release_date
                 info['last_modified'] = date
 
             output[info['name']] = info