diff --git a/github3/gists/gist.py b/github3/gists/gist.py
index 7ea3949f8..9324ff7a6 100644
--- a/github3/gists/gist.py
+++ b/github3/gists/gist.py
@@ -126,7 +126,7 @@ def delete(self):
         return self._boolean(self._delete(self._api), 204, 404)
 
     @requires_auth
-    def edit(self, description='', files={}):
+    def edit(self, description='', files=None):
         """Edit this gist.
 
         :param str description: (optional), description of the gist
@@ -138,6 +138,8 @@ def edit(self, description='', files={}):
         :returns: bool -- whether the edit was successful
 
         """
+        if files is None:
+                files = {}
         data = {}
         json = None
         if description:
diff --git a/github3/github.py b/github3/github.py
index 184ffbba0..51c6fa85e 100644
--- a/github3/github.py
+++ b/github3/github.py
@@ -68,13 +68,15 @@ def _repr(self):
         return '<GitHub at 0x{0:x}>'.format(id(self))
 
     @requires_auth
-    def add_email_addresses(self, addresses=[]):
+    def add_email_addresses(self, addresses=None):
         """Add the email addresses in ``addresses`` to the authenticated
         user's account.
 
         :param list addresses: (optional), email addresses to be added
         :returns: list of :class:`~github3.users.Email`
         """
+        if addresses is None:
+                addresses = []
         json = []
         if addresses:
             url = self._build_url('user', 'emails')
@@ -252,7 +254,7 @@ def create_gist(self, description, files, public=True):
 
     @requires_auth
     def create_issue(self, owner, repository, title, body=None, assignee=None,
-                     milestone=None, labels=[]):
+                     milestone=None, labels=None):
         """Create an issue on the project 'repository' owned by 'owner'
         with title 'title'.
 
@@ -280,6 +282,8 @@ def create_issue(self, owner, repository, title, body=None, assignee=None,
         :param list labels: (optional), List of label names.
         :returns: :class:`Issue <github3.issues.Issue>` if successful
         """
+        if labels is None:
+                labels = []
         repo = None
         if owner and repository and title:
             repo = self.repository(owner, repository)
@@ -347,13 +351,15 @@ def create_repository(self, name, description='', homepage='',
         return self._instance_or_null(Repository, json)
 
     @requires_auth
-    def delete_email_addresses(self, addresses=[]):
+    def delete_email_addresses(self, addresses=None):
         """Delete the email addresses in ``addresses`` from the
         authenticated user's account.
 
         :param list addresses: (optional), email addresses to be removed
         :returns: bool
         """
+        if addresses is None:
+                addresses = []
         url = self._build_url('user', 'emails')
         return self._boolean(self._delete(url, data=json.dumps(addresses)),
                              204, 404)
diff --git a/github3/orgs.py b/github3/orgs.py
index 0b8cda6a9..6be02e8db 100644
--- a/github3/orgs.py
+++ b/github3/orgs.py
@@ -385,7 +385,7 @@ def conceal_member(self, username):
         return self._boolean(self._delete(url), 204, 404)
 
     @requires_auth
-    def create_team(self, name, repo_names=[], permission=''):
+    def create_team(self, name, repo_names=None, permission=''):
         """Create a new team and return it.
 
         This only works if the authenticated user owns this organization.
@@ -404,6 +404,8 @@ def create_team(self, name, repo_names=[], permission=''):
 
         :returns: :class:`Team <Team>`
         """
+        if repo_names is None:
+                repo_names = []
         data = {'name': name, 'repo_names': repo_names,
                 'permission': permission}
         url = self._build_url('teams', base_url=self._api)
diff --git a/github3/repos/hook.py b/github3/repos/hook.py
index 03db7f1eb..ce7c69fec 100644
--- a/github3/repos/hook.py
+++ b/github3/repos/hook.py
@@ -58,7 +58,7 @@ def delete(self):
         return self._boolean(self._delete(self._api), 204, 404)
 
     @requires_auth
-    def edit(self, config={}, events=[], add_events=[], rm_events=[],
+    def edit(self, config=None, events=None, add_events=None, rm_events=None,
              active=True):
         """Edit this hook.
 
@@ -73,6 +73,14 @@ def edit(self, config={}, events=[], add_events=[], rm_events=[],
         :param bool active: (optional), should this event be active
         :returns: bool
         """
+        if config is None:
+                config = {}
+        if events is None:
+                events = []
+        if add_events is None:
+                add_events = []
+        if rm_events is None:
+                rm_events = []
         data = {'config': config, 'active': active}
         if events:
             data['events'] = events
diff --git a/github3/repos/repo.py b/github3/repos/repo.py
index 33f94dd47..b4e03b533 100644
--- a/github3/repos/repo.py
+++ b/github3/repos/repo.py
@@ -766,7 +766,7 @@ def create_fork(self, organization=None):
         return self._instance_or_null(Repository, json)
 
     @requires_auth
-    def create_hook(self, name, config, events=['push'], active=True):
+    def create_hook(self, name, config, events=None, active=True):
         """Create a hook on this repository.
 
         :param str name: (required), name of the hook
@@ -778,6 +778,8 @@ def create_hook(self, name, config, events=['push'], active=True):
         :returns: :class:`Hook <github3.repos.hook.Hook>` if successful,
             otherwise None
         """
+        if events is None:
+                events = ['push']
         json = None
         if name and config and isinstance(config, dict):
             url = self._build_url('hooks', base_url=self._api)