diff --git a/lib/faker_maker.rb b/lib/faker_maker.rb
index 50e6d96..c2cafa6 100644
--- a/lib/faker_maker.rb
+++ b/lib/faker_maker.rb
@@ -29,7 +29,10 @@ class NoSuchFactoryError < StandardError; end
   class NoSuchAttributeError < StandardError; end
   class ChaosConflictingAttributeError < StandardError; end
   class NoSuchAttributeNamingStrategy < StandardError; end
-  # Your code goes here...
+
+  # Token value for marking attributes as omittable from generated JSON.
+  # Usage in factory definitions: `omit: FakerMaker::OMIT`
+  OMIT = '__OMIT__'.freeze
 
   module_function
 
diff --git a/lib/faker_maker/factory.rb b/lib/faker_maker/factory.rb
index b023c02..f1c578e 100644
--- a/lib/faker_maker/factory.rb
+++ b/lib/faker_maker/factory.rb
@@ -208,6 +208,13 @@ def populate_instance( instance, attr_override_values, chaos: false )
       FakerMaker[parent].populate_instance(instance, attr_override_values, chaos:) if parent?
 
       attributes = chaos ? chaos_select(chaos) : @attributes
+      # When chaos is enabled, protect explicitly overridden attributes from being affected by chaos;
+      # what you pass in is what you get.
+      if chaos
+        override_attrs = @attributes.select { |attr| attr_override_values.key?( attr.name ) }
+        attributes = (attributes + override_attrs).uniq
+        attributes = @attributes.select { |attr| attributes.include?( attr ) }
+      end
 
       attributes.each do |attribute|
         value = value_for_attribute( instance, attribute, attr_override_values, chaos: )
diff --git a/lib/faker_maker/version.rb b/lib/faker_maker/version.rb
index a497f67..149cf69 100644
--- a/lib/faker_maker/version.rb
+++ b/lib/faker_maker/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module FakerMaker
-  VERSION = '4.0.0'
+  VERSION = '5.0.0'
 end
diff --git a/spec/faker_maker/attribute_spec.rb b/spec/faker_maker/attribute_spec.rb
index 632a48e..c758598 100644
--- a/spec/faker_maker/attribute_spec.rb
+++ b/spec/faker_maker/attribute_spec.rb
@@ -67,10 +67,22 @@
     expect( attr.omit?('anything') ).to be true
   end
 
-  it 'can omit nils and empty' do
-    attr = FakerMaker::Attribute.new( :my_name, nil, omit: %i[nil empty] )
+  it 'can omit using the OMIT token' do
+    attr = FakerMaker::Attribute.new( :my_name, nil, omit: FakerMaker::OMIT )
+    expect( attr.omit?(FakerMaker::OMIT) ).to be true
+  end
+
+  it 'does not omit nil or empty when using the OMIT token' do
+    attr = FakerMaker::Attribute.new( :my_name, nil, omit: FakerMaker::OMIT )
+    expect( attr.omit?(nil) ).to be false
+    expect( attr.omit?('') ).to be false
+  end
+
+  it 'can omit nils, empty and the OMIT token' do
+    attr = FakerMaker::Attribute.new( :my_name, nil, omit: [:nil, :empty, FakerMaker::OMIT] )
     expect( attr.omit?('') ).to be true
     expect( attr.omit?(nil) ).to be true
+    expect( attr.omit?(FakerMaker::OMIT) ).to be true
     expect( attr.omit?('anything') ).to be false
   end
 
diff --git a/spec/faker_maker/factory_spec.rb b/spec/faker_maker/factory_spec.rb
index 4c519da..c3da1fb 100644
--- a/spec/faker_maker/factory_spec.rb
+++ b/spec/faker_maker/factory_spec.rb
@@ -279,6 +279,24 @@
         factory.build( chaos: %i[required_attribute] )
       end.to raise_error(FakerMaker::ChaosConflictingAttributeError)
     end
+
+    it 'preserves explicitly overridden attributes when chaos is enabled' do
+      factory = FakerMaker::Factory.new( :example_factory )
+      required_attribute = FakerMaker::Attribute.new( :required_attribute, proc { 'required' }, required: true )
+      optional_attribute = FakerMaker::Attribute.new( :optional_attribute, proc { 'optional' } )
+      factory.attach_attribute( required_attribute )
+      factory.attach_attribute( optional_attribute )
+      FakerMaker.register_factory( factory )
+
+      fakes = []
+      10.times do
+        fakes << factory.build( attributes: { optional_attribute: 'overridden' }, chaos: true )
+      end
+
+      fakes.each do |fake|
+        expect( fake.optional_attribute ).to eq 'overridden'
+      end
+    end
   end
 
   describe '#instance' do
diff --git a/usefakermaker.com.site/site/src/docs/usage/chaos/index.page.md b/usefakermaker.com.site/site/src/docs/usage/chaos/index.page.md
index d561490..0206846 100644
--- a/usefakermaker.com.site/site/src/docs/usage/chaos/index.page.md
+++ b/usefakermaker.com.site/site/src/docs/usage/chaos/index.page.md
@@ -36,3 +36,15 @@ You can also specify which attributes Chaos can use when instantiating your obje
 ```ruby
 result = FakerMaker[:item].build( chaos: %i[name manufacturer] )
 ```
+
+## Overrides are preserved
+
+When you pass override attributes at build time, Chaos will not touch them. What you pass in is what you get.
+
+```ruby
+result = FakerMaker[:item].build( attributes: { name: 'Specific Name' }, chaos: true )
+result.name
+=> "Specific Name"
+```
+
+Even though `name` is optional and Chaos might otherwise remove it, explicitly overriding it guarantees it will be present with the value you specified.
diff --git a/usefakermaker.com.site/site/src/docs/usage/destroying-factories/index.page.md b/usefakermaker.com.site/site/src/docs/usage/destroying-factories/index.page.md
index 7e1a5b7..98fafb4 100644
--- a/usefakermaker.com.site/site/src/docs/usage/destroying-factories/index.page.md
+++ b/usefakermaker.com.site/site/src/docs/usage/destroying-factories/index.page.md
@@ -25,7 +25,7 @@ FakerMaker.factory :user do
 end
 
 FM[:user].as_json
- => {:name=>"Patsy Stone"}
+=> {:name=>"Patsy Stone"}
 ```
 
 On the other hand, sometimes you really, really want to destroy a factory and start again (especially if you are experimenting in a REPL for example). FakerMaker allows you to shut a factory which will de-register it from the list of available factories and attempt to unload the class it has built from the Ruby interpreter.
@@ -43,7 +43,7 @@ FakerMaker.factory :user do
 end
 
 FM[:user].as_json
- => {:name=>"Patsy Stone", :email=>"patsy@fabulous.co.uk"}
- ```
+=> {:name=>"Patsy Stone", :email=>"patsy@fabulous.co.uk"}
+```
 
  It also provides the `shut_all!` method to remove all factories.
diff --git a/usefakermaker.com.site/site/src/docs/usage/getting-started/index.page.md b/usefakermaker.com.site/site/src/docs/usage/getting-started/index.page.md
index db2716c..ea6e124 100644
--- a/usefakermaker.com.site/site/src/docs/usage/getting-started/index.page.md
+++ b/usefakermaker.com.site/site/src/docs/usage/getting-started/index.page.md
@@ -53,5 +53,5 @@ FakerMaker.factory :request do
 end
 
 FakerMaker[:request].build.body
-# => nil
+=> nil
 ```
diff --git a/usefakermaker.com.site/site/src/docs/usage/json-field-names/index.page.md b/usefakermaker.com.site/site/src/docs/usage/json-field-names/index.page.md
index b135ec8..2451328 100644
--- a/usefakermaker.com.site/site/src/docs/usage/json-field-names/index.page.md
+++ b/usefakermaker.com.site/site/src/docs/usage/json-field-names/index.page.md
@@ -23,7 +23,7 @@ v.engine_capacity = 125
 
 v.to_json
 
-=> "{\"wheels\":4,\"colour\":\"blue\",\"engineCapacity\":125}"
+ => "{\"wheels\":4,\"colour\":\"blue\",\"engineCapacity\":125}"
 ```
 
 ## Per-attribute naming
diff --git a/usefakermaker.com.site/site/src/docs/usage/omitting-fields/index.page.md b/usefakermaker.com.site/site/src/docs/usage/omitting-fields/index.page.md
index 5d306de..6ee26a0 100644
--- a/usefakermaker.com.site/site/src/docs/usage/omitting-fields/index.page.md
+++ b/usefakermaker.com.site/site/src/docs/usage/omitting-fields/index.page.md
@@ -12,17 +12,18 @@ end
 FM[:user].build.as_json
 => {:name=>"Patsy Stone", :email=>"patsy@fabulous.co.uk", :admin=>false}
 
-FM[:user].build(email: nil).as_json
+FM[:user].build( attributes: { email: nil } ).as_json
 => {:name=>"Patsy Stone", :admin=>false}
 ```
 
 The `omit` modifier can take a single value or an array. If it is passed a value and the attribute equals this value, it will not be included in the output from `as_json` (which returns a Ruby Hash) or in `to_json` methods.
 
-There are three special modifiers:
+There are four special modifiers:
 
-* `:nil` (symbol) to omit output when the attribute is set to nil
-* `:empty` to omit output when the value is an empty string, an empty array or an empty hash
+* `:nil` (symbol) to omit output when the attribute is set to nil.
+* `:empty` to omit output when the value is an empty string, an empty array or an empty hash.
 * `:always` to never output this attribute.
+* `FakerMaker::OMIT` to omit output only when the attribute is set to this token value.
 
 These can be mixed with real values, e.g.
 
@@ -33,3 +34,26 @@ FakerMaker.factory :user do
   admin {false}
 end
 ```
+
+## Using the omit token
+
+You may want to exclude a field but still allow it to be set to `nil`, an empty string/array/hash, or any other value.
+
+`FakerMaker::OMIT` is a token value that can provide this flexibility, e.g.
+
+```ruby
+FakerMaker.factory :user do
+  name(omit: FakerMaker::OMIT) {'Patsy Stone'}
+  email(omit: :nil) {'patsy@fabulous.co.uk'}
+  admin(omit: :empty) {false}
+end
+
+FM[:user].build( attributes: { name: FakerMaker::OMIT } ).as_json
+=> {:email=>"patsy@fabulous.co.uk", :admin=>false}
+
+FM[:user].build( attributes: { name: nil, email: nil } ).as_json
+=> {:name=>nil, :admin=>false}
+
+FM[:user].build( attributes: { name: '', admin: '' } ).as_json
+=> {:name=>"", :email=>"patsy@fabulous.co.uk"}
+```