diff --git a/Readme.md b/Readme.md
index 0e6b1c19..6a3e2a5b 100755
--- a/Readme.md
+++ b/Readme.md
@@ -736,6 +736,12 @@ You can mark the `owner_id` field as required in the database by specifying the
 Animal.hasOne("owner", Person, { required: true });
 ```
 
+If a field is not required, but should be validated even if it is not present, then specify the `alwaysValidate` option.
+(this can happen, for example when validation of a null field depends on other fields in the record)
+```js
+Animal.hasOne("owner", Person, { required: false, alwaysValidate: true });
+```
+
 If you prefer to use another name for the field (owner_id) you can change this parameter in the settings.
 
 ```js
diff --git a/lib/Instance.js b/lib/Instance.js
index 609c4cd5..beefce89 100755
--- a/lib/Instance.js
+++ b/lib/Instance.js
@@ -54,6 +54,7 @@ function Instance(Model, opts) {
 
 				if (Model.allProperties[k]) {
 					required = Model.allProperties[k].required;
+					alwaysValidate = Model.allProperties[k].alwaysValidate;
 				} else {
 					for (i = 0; i < opts.one_associations.length; i++) {
 						if (opts.one_associations[i].field === k) {
@@ -62,8 +63,7 @@ function Instance(Model, opts) {
 						}
 					}
 				}
-
-				if (!required && instance[k] == null) {
+				if (!alwaysValidate && !required && instance[k] == null) {
 					continue; // avoid validating if property is not required and is "empty"
 				}
 				for (i = 0; i < opts.validations[k].length; i++) {
diff --git a/test/integration/validation.js b/test/integration/validation.js
index 8482f0f7..8e5edb18 100644
--- a/test/integration/validation.js
+++ b/test/integration/validation.js
@@ -9,6 +9,7 @@ var ORM      = require('../../');
 describe("Validations", function() {
 	var db = null;
 	var Person = null;
+	var Person2 = null;
 
 	var setup = function (returnAll, required) {
 		return function (done) {
@@ -17,7 +18,7 @@ describe("Validations", function() {
 
 			Person = db.define("person", {
 				name:   { type: 'text'   },
-				height: { type: 'number' }
+				height: { type: 'number' },
 			}, {
 				validations: {
 					name:   ORM.validators.rangeLength(3, 30),
@@ -29,6 +30,29 @@ describe("Validations", function() {
 		};
 	};
 
+	notNull = function(val, next, data) {
+		if (val != null) {
+			return next('notnull');
+		}
+		return next();
+	};
+	var setupAlwaysValidate = function () {
+		return function (done) {
+			Person2 = db.define("person2", {
+				name:   { type: 'text'   },
+				mustbenull: { type: 'text', required:false, alwaysValidate: true }
+				, canbenull: { type: 'text', required:false }
+			}, {
+				validations: {
+					name:   ORM.validators.rangeLength(3, 30),
+					mustbenull: notNull,
+					canbenull: notNull
+				}
+			});
+			return helper.dropSync(Person2, done);
+		};
+	};
+
 	before(function (done) {
 		helper.connect(function (connection) {
 			db = connection;
@@ -40,6 +64,32 @@ describe("Validations", function() {
 		db.close();
 	});
 
+
+	describe("alwaysValidate", function () {
+		before(setupAlwaysValidate());
+
+		it("I want to see it fail first (the absence of evidence)", function(done) {
+			var rachel = new Person2({name: 'rachel', canbenull:null, mustbenull:null});
+			rachel.save(function (err) {
+				should.not.exist(err);
+				return done();
+			});
+		});
+
+		it("then it should work", function(done) {
+			var tom = new Person2({name: 'tom', canbenull:null, mustbenull:'notnull'});
+			tom.save(function (err) {
+				should.exist(err);
+				should.equal(typeof err,   "object");
+				should.equal(err.property, "mustbenull");
+				should.equal(err.msg,      "notnull");
+				should.equal(err.type,     "validation");
+				should.equal(tom.id,      null);
+				return done();
+			});
+		});
+	});
+
 	describe("predefined", function () {
 		before(setup(false, false));
 
@@ -59,7 +109,7 @@ describe("Validations", function() {
 		});
 
 		describe("unique", function () {
-		    if (protocol === "mongodb") return;
+			if (protocol === "mongodb") return;
 
 			var Product = null;
 
@@ -77,8 +127,6 @@ describe("Validations", function() {
 							productId : ORM.validators.unique() // this must be straight after a required & validated row.
 						}
 					});
-					Product.hasOne('product', Product, { field: 'productId', required: false, autoFetch: true });
-
 					return helper.dropSync(Product, done);
 				};
 			};
@@ -220,6 +268,7 @@ describe("Validations", function() {
 						});
 					});
 				});
+
 			});
 		});
 	});
@@ -363,4 +412,7 @@ describe("Validations", function() {
 			});
 		});
 	});
+
+
 });
+