diff --git a/lti_provider/mixins.py b/lti_provider/mixins.py
index 0235bff..098415b 100644
--- a/lti_provider/mixins.py
+++ b/lti_provider/mixins.py
@@ -24,7 +24,7 @@ def join_groups(self, request, lti, ctx):
                 request.user.groups.add(ctx.faculty_group)
                 break
 
-            if settings.LTI_TOOL_CONFIGURATION['allow_ta_access']:
+            if settings.LTI_TOOL_CONFIGURATION.get('allow_ta_access', False):
                 if 'teachingassistant' in role:
                     request.user.groups.add(ctx.faculty_group)
                     break
diff --git a/lti_provider/tests/test_views.py b/lti_provider/tests/test_views.py
index 3d001cd..07395ef 100644
--- a/lti_provider/tests/test_views.py
+++ b/lti_provider/tests/test_views.py
@@ -95,6 +95,22 @@ def test_join_groups_teachingassistant_true(self):
             self.assertTrue(user in ctx.group.user_set.all())
             self.assertTrue(user in ctx.faculty_group.user_set.all())
 
+    def test_missing_configuration(self):
+        mixin = LTIAuthMixin()
+        ctx = LTICourseContextFactory()
+        user = UserFactory()
+        self.request.user = user
+        lti_tool_config2 = TEST_LTI_TOOL_CONFIGURATION.copy()
+        del lti_tool_config2['allow_ta_access']
+
+        with self.settings(
+                LTI_TOOL_CONFIGURATION=lti_tool_config2):
+            self.request.session['roles'] = \
+                u'urn:lti:role:ims/lis/TeachingAssistant'
+            mixin.join_groups(self.request, self.lti, ctx)
+            self.assertTrue(user in ctx.group.user_set.all())
+            self.assertFalse(user in ctx.faculty_group.user_set.all())
+
     def test_launch_invalid_user(self):
         request = generate_lti_request()
 
diff --git a/lti_provider/views.py b/lti_provider/views.py
index ced79e3..5d11366 100644
--- a/lti_provider/views.py
+++ b/lti_provider/views.py
@@ -120,7 +120,7 @@ def get_context_data(self, **kwargs):
         url = settings.LTI_TOOL_CONFIGURATION['landing_url'].format(
             self.request.scheme, domain, self.lti.course_context(self.request))
         is_auth_ta = None
-        if settings.LTI_TOOL_CONFIGURATION['allow_ta_access']:
+        if settings.LTI_TOOL_CONFIGURATION.get('allow_ta_access', False):
             role = self.request.session.get('roles', '').lower()
             is_auth_ta = 'teachingassistant' in role