diff --git a/app/models/settings.rb b/app/models/settings.rb
index 5ecaf01c88..9ede2b9913 100644
--- a/app/models/settings.rb
+++ b/app/models/settings.rb
@@ -28,7 +28,7 @@ def self.columns
   end
 
   def self.non_null_columns_names
-    columns.select { |column| column.null == false }.map(&:name)
+    columns.select { |column| !column.null }.map(&:name)
   end
 
   def approval_required_editable?
@@ -39,10 +39,14 @@ def approval_required_disabled?
     not_custom_account_plans.size > 1 && account_plans_ui_visible?
   end
 
+  def assign_attributes(attrs, options = {})
+    super(sanitize_attributes(attrs), options)
+  end
+
   def update(attrs)
     update_approval_required(attrs) if approval_required_editable?
 
-    super(sanitize_attributes(attrs))
+    super(attrs)
   end
 
   def set_forum_enabled
diff --git a/test/integration/admin/api/settings_controller_test.rb b/test/integration/admin/api/settings_controller_test.rb
index cda3488edc..71dde25753 100644
--- a/test/integration/admin/api/settings_controller_test.rb
+++ b/test/integration/admin/api/settings_controller_test.rb
@@ -33,7 +33,7 @@ def setup
 
   test 'update' do
     params = { access_token: token, signups_enabled: false, change_account_plan_permission: 'invalid', change_service_plan_permission: 'invalid'}
-    assert 'request', settings.change_account_plan_permission
+    assert_equal 'request', settings.change_account_plan_permission
     assert settings.signups_enabled
 
     put admin_api_settings_path(format: :json), params: params
@@ -50,8 +50,8 @@ def setup
     assert_response :success
 
     settings.reload
-    assert 'direct', settings.change_account_plan_permission
-    assert 'none', settings.change_service_plan_permission
+    assert_equal 'direct', settings.change_account_plan_permission
+    assert_equal 'none', settings.change_service_plan_permission
     assert_not settings.signups_enabled
   end
 
diff --git a/test/unit/settings_test.rb b/test/unit/settings_test.rb
index 3b1c448367..88262a27fb 100644
--- a/test/unit/settings_test.rb
+++ b/test/unit/settings_test.rb
@@ -179,15 +179,21 @@ def test_require_cc_on_signup_visible_ui_switch_on_rolling_updates
     assert settings.monthly_billing_enabled
   end
 
-  test 'empty values sanitized for non-null columns' do
+  test 'empty values are skipped for non-null columns' do
     settings.update(public_search: true)
     assert settings.reload.public_search
 
     settings.update(public_search: "")
+    assert_not settings.previous_changes[:public_search]
     assert settings.reload.public_search
 
     settings.update(public_search: nil)
+    assert_not settings.previous_changes[:public_search]
     assert settings.reload.public_search
+
+    settings.update(public_search: "false")
+    assert settings.previous_changes[:public_search]
+    assert_not settings.reload.public_search
   end
 
   test "validate change plan permission values" do