diff --git a/.travis.yml b/.travis.yml
index 6487ac8..6983520 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,4 @@
+sudo: false
 language: node_js
 before_install: npm install -g grunt-cli
 node_js:
diff --git a/readme.md b/readme.md
index d607791..b506351 100644
--- a/readme.md
+++ b/readme.md
@@ -123,6 +123,7 @@ By default, a checkbox will return a boolean value signifying whether or not it
 <form>
   <input type="checkbox" name="a">
   <input type="checkbox" name="b" checked>
+  <input type="checkbox" name="c" indeterminate>
 </form>
 ```
 
@@ -133,7 +134,8 @@ Backbone.Syphon.serialize(view);
 
 {
   a: false,
-  b: true
+  b: true,
+  c: null
 }
 ```
 
@@ -437,6 +439,7 @@ For more information on Key Assignment Validators, see the full
 There some known limitations in Backbone.Syphon, partially by design and partially implemented as default behaviors.
 
 * An input of type `checkbox` will return a boolean value. This can be overriden by replacing the Input Reader for checkboxes.
+* Yo avoid circular references, care should be taken when using Backbone.Relational. See (#33)[https://github.com/marionettejs/backbone.syphon/issues/33].
 
 ## Building Backbone.Syphon
 
diff --git a/spec/javascripts/deserialize.spec.js b/spec/javascripts/deserialize.spec.js
index f73914b..e2f9454 100644
--- a/spec/javascripts/deserialize.spec.js
+++ b/spec/javascripts/deserialize.spec.js
@@ -96,6 +96,34 @@ describe('deserializing an object into a form', function() {
     });
   });
 
+  describe('when deserializing into a multi-select box', function() {
+    beforeEach(function() {
+      this.View = Backbone.View.extend({
+        render: function() {
+          this.$el.html(
+              '<form>' +
+              '<select name="foo[]" multiple="multiple">' +
+              '<option value="bar1">Bar 1</option>' +
+              '<option value="bar2">Bar 2</option>' +
+              '<option value="bar3">Bar 3</option>' +
+              '</select>' +
+              '</form>'
+          );
+        }
+      });
+
+      this.view = new this.View();
+      this.view.render();
+
+      Backbone.Syphon.deserialize(this.view, {foo: ['bar1', 'bar2']});
+      this.result = this.view.$('select').val();
+    });
+
+    it('should select the options corresponding to the values in the given object', function() {
+      expect(this.result).to.deep.equal(['bar1', 'bar2']);
+    });
+  });
+
   describe('when deserializing into a checkbox', function() {
     beforeEach(function() {
       this.View = Backbone.View.extend({
@@ -137,6 +165,21 @@ describe('deserializing an object into a form', function() {
         expect(this.result).to.be.false;
       });
     });
+
+    describe('and the corresponding value in the given object is null', function() {
+      beforeEach(function() {
+        this.view = new this.View();
+        this.view.render();
+        this.view.$('#the-checkbox').prop('checked', false);
+
+        Backbone.Syphon.deserialize(this.view, {chk: null});
+        this.result = this.view.$('#the-checkbox').prop('indeterminate');
+      });
+
+      it('should add an indeterminate attribute', function() {
+        expect(this.result).to.be.true;
+      });
+    });
   });
 
   describe('when deserializing into a button', function() {
diff --git a/spec/javascripts/serialize.spec.js b/spec/javascripts/serialize.spec.js
index 4931e9d..47e45b3 100644
--- a/spec/javascripts/serialize.spec.js
+++ b/spec/javascripts/serialize.spec.js
@@ -114,11 +114,38 @@ describe('serializing a form', function() {
       this.result = Backbone.Syphon.serialize(this.view);
     });
 
-    it('should have the textarea\'s value', function() {
+    it('should return the selected option value', function() {
       expect(this.result.foo).to.equal('bar');
     });
   });
 
+  describe('when serializing a multi-select box', function() {
+    beforeEach(function() {
+      this.View = Backbone.View.extend({
+        render: function() {
+          this.$el.html(
+              '<form>' +
+              '<select name="foo[]" multiple="multiple">' +
+              '<option value="bar1" selected="selected">Bar 1</option>' +
+              '<option value="bar2">Bar 2</option>' +
+              '<option value="bar3" selected="selected">Bar 3</option>' +
+              '</select>' +
+              '</form>'
+          );
+        }
+      });
+
+      this.view = new this.View();
+      this.view.render();
+
+      this.result = Backbone.Syphon.serialize(this.view);
+    });
+
+    it('should return the selected options values', function() {
+      expect(this.result.foo).to.deep.equal(['bar1', 'bar3']);
+    });
+  });
+
   describe('when serializing a checkbox', function() {
     beforeEach(function() {
       this.View = Backbone.View.extend({
@@ -158,6 +185,20 @@ describe('serializing a form', function() {
         expect(this.result.chk).to.be.false;
       });
     });
+
+    describe('and the checkbox is indeterminate', function() {
+      beforeEach(function() {
+        this.view = new this.View();
+        this.view.render();
+        this.view.$('#the-checkbox').prop('indeterminate', true);
+
+        this.result = Backbone.Syphon.serialize(this.view);
+      });
+
+      it('should return an object with a value of null', function() {
+        expect(this.result.chk).to.be.null;
+      });
+    });
   });
 
   describe('when serializing a button', function() {
diff --git a/src/backbone.syphon.inputreaders.js b/src/backbone.syphon.inputreaders.js
index ccca818..2636d28 100644
--- a/src/backbone.syphon.inputreaders.js
+++ b/src/backbone.syphon.inputreaders.js
@@ -17,5 +17,5 @@ InputReaders.registerDefault(function($el) {
 // Checkbox reader, returning a boolean value for
 // whether or not the checkbox is checked.
 InputReaders.register('checkbox', function($el) {
-  return $el.prop('checked');
+  return ($el.prop('indeterminate')) ? null : $el.prop('checked');
 });
diff --git a/src/backbone.syphon.inputwriters.js b/src/backbone.syphon.inputwriters.js
index 7affde5..a84b828 100644
--- a/src/backbone.syphon.inputwriters.js
+++ b/src/backbone.syphon.inputwriters.js
@@ -17,7 +17,11 @@ InputWriters.registerDefault(function($el, value) {
 // Checkbox writer, set whether or not the checkbox is checked
 // depending on the boolean value.
 InputWriters.register('checkbox', function($el, value) {
-  $el.prop('checked', value);
+  if (value === null) {
+    $el.prop('indeterminate', true);
+  } else {
+    $el.prop('checked', value);
+  }
 });
 
 // Radio button writer, set whether or not the radio button is
diff --git a/src/backbone.syphon.js b/src/backbone.syphon.js
index f15d9e3..ab37a8f 100644
--- a/src/backbone.syphon.js
+++ b/src/backbone.syphon.js
@@ -202,11 +202,15 @@ var assignKeyValue = function(obj, keychain, value) {
 
   // if it's the last key in the chain, assign the value directly
   if (keychain.length === 0) {
-    if (_.isArray(obj[key])) {
-      obj[key].push(value);
-    } else {
-      obj[key] = value;
-    }
+    value = _.isArray(value) ? value : [value];
+
+    _.each(value, function(v) {
+      if (_.isArray(obj[key])) {
+        obj[key].push(v);
+      } else {
+        obj[key] = v;
+      }
+    });
   }
 
   // recursive parsing of the array, depth-first