diff --git a/lib/mysql.js b/lib/mysql.js
index 38d76aa..8547fad 100644
--- a/lib/mysql.js
+++ b/lib/mysql.js
@@ -324,6 +324,9 @@ MySQL.prototype.toDatabase = function (prop, val, forCreate) {
     return this.client.escape(val);
   }
   if (prop.type === Number) {
+    if (isNaN(val)) {
+      return 'NULL';
+    }
     return this.client.escape(val);
   }
   if (prop.type === Date) {
@@ -508,7 +511,11 @@ MySQL.prototype._buildWhere = function (model, conds) {
       sqlCond += (condType === 'inq' || condType === 'nin') ? '(' + val + ')' : val;
       cs.push(sqlCond);
     } else {
-      cs.push(keyEscaped + ' = ' + val);
+      if (val === 'NULL') {
+        cs.push(keyEscaped + ' IS NULL');
+      } else {
+        cs.push(keyEscaped + ' = ' + val);
+      }
     }
   });
   if (cs.length === 0) {
@@ -595,6 +602,19 @@ MySQL.prototype.all = function all(model, filter, callback) {
 
 };
 
+MySQL.prototype.find = function find(model, id, callback) {
+  var idName = this.idName(model);
+  var filter = {where: {}, limit: 1};
+  filter.where[idName] = id;
+  this.all(model, filter, function(err, results) {
+    if (err) {
+      return callback && callback(err);
+    } else {
+      return callback && callback(results && results[0]);
+    }
+  });
+};
+
 MySQL.prototype.count = function count(model, callback, where) {
 
   this.query('SELECT count(*) as cnt FROM ' +
diff --git a/test/mysql.test.js b/test/mysql.test.js
index af1c3dc..a86b3c3 100644
--- a/test/mysql.test.js
+++ b/test/mysql.test.js
@@ -455,6 +455,18 @@ describe('mysql', function () {
       });
   });
 
+  it('should convert NaN to NULL for query', function(done) {
+    Post.create({title: 'My Post1', content: 'Hello', stars: 5},
+      function(err, post) {
+        Post.findById('x',
+          function(err, post) {
+            should.not.exist(err);
+            should.not.exist(post);
+            done();
+          });
+      });
+  });
+
   it('should not allow duplicate titles', function (done) {
     var data = {title: 'a', content: 'AAA'};
     PostWithUniqueTitle.create(data, function (err, post) {