diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9166533..86830f8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## Unreleased
+
+* Default `form_with` extension's `:model` option to `false` instead of `nil` [@seanpdoyle]
+
 ## 1.9.0
 
 * Added support for `form_with` [@DialBird]
diff --git a/lib/html5_validators/action_view/form_helpers.rb b/lib/html5_validators/action_view/form_helpers.rb
index 952c048..52c132e 100644
--- a/lib/html5_validators/action_view/form_helpers.rb
+++ b/lib/html5_validators/action_view/form_helpers.rb
@@ -13,7 +13,7 @@ def form_for(record, options = {}, &block)
       end
 
       if Rails::VERSION::STRING >= '5.1'
-        def form_with(model: nil, scope: nil, url: nil, format: nil, **options)
+        def form_with(model: false, scope: nil, url: nil, format: nil, **options)
           if model && model.respond_to?(:auto_html5_validation=)
             if !Html5Validators.enabled || (options[:auto_html5_validation] == false)
               model.auto_html5_validation = false
diff --git a/test/fake_app.rb b/test/fake_app.rb
index d1097e2..ebed084 100644
--- a/test/fake_app.rb
+++ b/test/fake_app.rb
@@ -32,6 +32,7 @@ class Html5ValidatorsTestApp < Rails::Application
       get :new_with_required_false
     end
   end
+  resources :forms, only: [:new, :create]
 end
 
 # models
@@ -213,6 +214,15 @@ def new_with_required_false
     ERB
   end
 end
+class FormsController < ApplicationController
+  def new
+    render inline: <<-ERB
+<%= form_with url: forms_path, id: 'form_with' do |f| %>
+<%= f.button %>
+<% end %>
+    ERB
+  end
+end
 
 # helpers
 module ApplicationHelper; end
diff --git a/test/features/active_model_validation_test.rb b/test/features/active_model_validation_test.rb
index 2154b2d..8e2d09d 100644
--- a/test/features/active_model_validation_test.rb
+++ b/test/features/active_model_validation_test.rb
@@ -125,4 +125,13 @@ class ActiveModelValidationTest < ActionDispatch::IntegrationTest
       end
     end
   end
+
+  if Rails::VERSION::STRING >= '5.1'
+    sub_test_case 'without model' do
+      test 'new form' do
+        visit '/forms/new'
+        assert page.has_css? '#form_with button'
+      end
+    end
+  end
 end