diff --git a/trains/backend_config/bucket_config.py b/trains/backend_config/bucket_config.py
index 3a855772..14d1a7d5 100644
--- a/trains/backend_config/bucket_config.py
+++ b/trains/backend_config/bucket_config.py
@@ -98,12 +98,12 @@ class S3BucketConfigurations(BaseBucketConfigurations):
     @classmethod
     def from_config(cls, s3_configuration):
         config_list = S3BucketConfig.from_list(
-            s3_configuration.get("credentials", default=None)
+            s3_configuration.get("credentials", [])
         )
 
-        default_key = s3_configuration.get("key", default="")
-        default_secret = s3_configuration.get("secret", default="")
-        default_region = s3_configuration.get("region", default="")
+        default_key = s3_configuration.get("key", "")
+        default_secret = s3_configuration.get("secret", "")
+        default_region = s3_configuration.get("region", "")
 
         default_key = _none_to_empty_string(default_key)
         default_secret = _none_to_empty_string(default_secret)
@@ -235,11 +235,11 @@ class GSBucketConfigurations(BaseBucketConfigurations):
         if gs_configuration is None:
             return cls()
 
-        config_list = gs_configuration.get("credentials", default=list())
+        config_list = gs_configuration.get("credentials", [])
         buckets_configs = [GSBucketConfig(**entry) for entry in config_list]
 
-        default_project = gs_configuration.get("project", default=None)
-        default_credentials = gs_configuration.get("credentials_json", default=None)
+        default_project = gs_configuration.get("project", {})
+        default_credentials = gs_configuration.get("credentials_json", {})
 
         return cls(buckets_configs, default_project, default_credentials)
 
diff --git a/trains/storage/helper.py b/trains/storage/helper.py
index b58db14b..a7ea3a66 100644
--- a/trains/storage/helper.py
+++ b/trains/storage/helper.py
@@ -157,8 +157,8 @@ class StorageHelper(object):
     _async_upload_threads = set()
 
     # collect all bucket credentials that aren't empty (ignore entries with an empty key or secret)
-    _s3_configurations = S3BucketConfigurations.from_config(config.get('aws.s3'))
-    _gs_configurations = GSBucketConfigurations.from_config(config.get('google.storage', default=None))
+    _s3_configurations = S3BucketConfigurations.from_config(config.get('aws.s3', {}))
+    _gs_configurations = GSBucketConfigurations.from_config(config.get('google.storage', {}))
 
     _path_substitutions = _PathSubstitutionRule.load_list_from_config()