diff --git a/plaid/api/accounts.py b/plaid/api/accounts.py
index deaef0443..0d8477efa 100644
--- a/plaid/api/accounts.py
+++ b/plaid/api/accounts.py
@@ -6,7 +6,7 @@ class Balance(API):
 
     def get(self,
             access_token,
-            _options={},
+            _options=None,
             account_ids=None):
         '''
         Retrieve real-time balance information for accounts.
@@ -15,8 +15,7 @@ def get(self,
         :param  [str]   account_ids:    A list of account_ids to retrieve for
                                         the item. Optional.
         '''
-        options = {}
-        options.update(_options)
+        options = _options or {}
         if account_ids is not None:
             options['account_ids'] = account_ids
 
@@ -41,7 +40,7 @@ def __init__(self, client):
 
     def get(self,
             access_token,
-            _options={},
+            _options=None,
             account_ids=None):
         '''
         Retrieve high-level account information for an Item.
@@ -50,8 +49,7 @@ def get(self,
         :param  [str]   account_ids:    A list of account_ids to retrieve for
                                         the item. Optional.
         '''
-        options = {}
-        options.update(_options)
+        options = _options or {}
         if account_ids is not None:
             options['account_ids'] = account_ids
 
diff --git a/plaid/api/assets.py b/plaid/api/assets.py
index 420cf1203..1b533bba5 100644
--- a/plaid/api/assets.py
+++ b/plaid/api/assets.py
@@ -12,7 +12,7 @@ def __init__(self, client):
     def create(self,
                access_tokens,
                days_requested,
-               options={}):
+               options=None):
         '''
         Create an asset report.
 
@@ -25,6 +25,7 @@ def create(self,
                                         information on the options object, see
                                         the documentation site listed above.
         '''
+        options = options or {}
 
         return self.client.post('/asset_report/create', {
             'access_tokens': access_tokens,
@@ -44,7 +45,6 @@ def filter(self,
                                                 exclude from the new Asset
                                                 Report.
         '''
-
         return self.client.post('/asset_report/filter', {
             'asset_report_token': asset_report_token,
             'account_ids_to_exclude': account_ids_to_exclude,
@@ -53,7 +53,7 @@ def filter(self,
     def refresh(self,
                 asset_report_token,
                 days_requested,
-                options={}):
+                options=None):
         '''
         Create a new, refreshed asset report based on an existing asset report.
 
@@ -65,6 +65,7 @@ def refresh(self,
         :param  dict  options:              An optional dictionary. This is the
                                             same object used in `create`.
         '''
+        options = options or {}
 
         return self.client.post('/asset_report/refresh', {
             'asset_report_token': asset_report_token,
diff --git a/plaid/api/auth.py b/plaid/api/auth.py
index ed93be768..5dc4be84e 100644
--- a/plaid/api/auth.py
+++ b/plaid/api/auth.py
@@ -6,7 +6,7 @@ class Auth(API):
 
     def get(self,
             access_token,
-            _options={},
+            _options=None,
             account_ids=None):
         '''
         Retrieve account and routing numbers for checking and savings accounts.
@@ -16,8 +16,7 @@ def get(self,
         :param  [str]   account_ids:    A list of account_ids to retrieve for
                                         the item. Optional.
         '''
-        options = {}
-        options.update(_options)
+        options = _options or {}
         if account_ids is not None:
             options['account_ids'] = account_ids
 
diff --git a/plaid/api/institutions.py b/plaid/api/institutions.py
index 43668650d..3966b6037 100644
--- a/plaid/api/institutions.py
+++ b/plaid/api/institutions.py
@@ -19,15 +19,17 @@ def get(self, count, offset=0):
             'offset': offset,
         })
 
-    def get_by_id(self, institution_id, _options={}):
+    def get_by_id(self, institution_id, _options=None):
         '''
         Fetch a single institution by id.
 
         :param  str     institution_id:
         '''
+        options = _options or {}
+
         return self.client.post_public_key('/institutions/get_by_id', {
             'institution_id': institution_id,
-            'options': _options,
+            'options': options,
         })
 
     def search(self, query, _options={}, products=None):
@@ -38,8 +40,10 @@ def search(self, query, _options={}, products=None):
                                     institutions.
         :param  [str]    products:  Filter FIs by available products. Optional.
         '''
+        options = _options or {}
+
         return self.client.post_public_key('/institutions/search', {
             'query': query,
             'products': products,
-            'options': _options,
+            'options': options,
         })
diff --git a/plaid/api/item.py b/plaid/api/item.py
index 0b23b8c08..0fbf858b6 100644
--- a/plaid/api/item.py
+++ b/plaid/api/item.py
@@ -4,7 +4,7 @@
 class Credentials(API):
     '''Item Credentials endpoints.'''
 
-    def update(self, access_token, credentials, _options={}):
+    def update(self, access_token, credentials, _options=None):
         '''
         Update the credentials associated with an item.
 
@@ -13,6 +13,8 @@ def update(self, access_token, credentials, _options={}):
 
         :param  dict     credentials:   See ``Item.create`` for details.
         '''
+        _options = _options or {}
+
         return self.client.post('/item/credentials/update', {
             'access_token': access_token,
             'credentials': credentials,
@@ -117,7 +119,7 @@ def create(self,
                credentials,
                institution_id,
                initial_products,
-               _options={},
+               _options=None,
                transactions__start_date=None,
                transactions__end_date=None,
                transactions__await_results=None,
@@ -155,8 +157,10 @@ def create(self,
 
         All dates should be formatted as ``YYYY-MM-DD``.
         '''
+        options = _options or {}
+
         transaction_options = {}
-        transaction_options.update(_options.get('transactions', {}))
+        transaction_options.update(options.get('transactions', {}))
         if transactions__start_date is not None:
             transaction_options['start_date'] = transactions__start_date
         if transactions__end_date is not None:
@@ -164,8 +168,6 @@ def create(self,
         if transactions__await_results is not None:
             transaction_options['await_results'] = transactions__await_results
 
-        options = {}
-        options.update(_options)
         if transaction_options:
             options['transactions'] = transaction_options
         if webhook is not None:
@@ -178,7 +180,7 @@ def create(self,
             'options': options,
         })
 
-    def mfa(self, access_token, mfa_type, responses, _options={}):
+    def mfa(self, access_token, mfa_type, responses, _options=None):
         '''
         Provide an MFA (Multi-Factor Authentication) response for an item.
 
@@ -186,6 +188,8 @@ def mfa(self, access_token, mfa_type, responses, _options={}):
         :param  str     mfa_type:       The type of mfa answered (e.g. device)
         :param  [str]   responses:      The MFA response(s)
         '''
+        _options = _options or {}
+
         return self.client.post('/item/mfa', {
             'access_token': access_token,
             'mfa_type': mfa_type,
diff --git a/plaid/api/sandbox.py b/plaid/api/sandbox.py
index d6ec755e2..618ee1bd4 100644
--- a/plaid/api/sandbox.py
+++ b/plaid/api/sandbox.py
@@ -21,7 +21,7 @@ class PublicToken(API):
     def create(self,
                institution_id,
                initial_products,
-               _options={},
+               _options=None,
                webhook=None):
         '''
         Generate a public token for sandbox testing.
@@ -32,8 +32,8 @@ def create(self,
 
         :param  str     webhook:
         '''
-        options = {}
-        options.update(_options)
+        options = _options or {}
+
         if webhook is not None:
             options['webhook'] = webhook
 
diff --git a/plaid/api/transactions.py b/plaid/api/transactions.py
index 5686d515d..1800ee428 100644
--- a/plaid/api/transactions.py
+++ b/plaid/api/transactions.py
@@ -8,7 +8,7 @@ def get(self,
             access_token,
             start_date,
             end_date,
-            _options={},
+            _options=None,
             account_ids=None,
             count=None,
             offset=None,
@@ -33,8 +33,8 @@ def get(self,
 
         All date should be formatted as ``YYYY-MM-DD``.
         '''
-        options = {}
-        options.update(_options)
+        options = _options or {}
+
         if account_ids is not None:
             options['account_ids'] = account_ids
         if count is not None: