diff --git a/lib/adapters/mysql.js b/lib/adapters/mysql.js
index 2fd19a06..5d464029 100644
--- a/lib/adapters/mysql.js
+++ b/lib/adapters/mysql.js
@@ -157,6 +157,9 @@ MySQL.prototype.toDatabase = function (prop, val) {
                     this.toDatabase(prop, val[1]);
         } else if (operator == 'inq' || operator == 'nin') {
             if (!(val.propertyIsEnumerable('length')) && typeof val === 'object' && typeof val.length === 'number') { //if value is array
+                for (var i = 0; i < val.length; i++) {
+                    val[i] = this.client.escape(val[i]);
+                }
                 return val.join(',');
             } else {
                 return val;
diff --git a/lib/adapters/postgres.js b/lib/adapters/postgres.js
index 1e634de1..4eefe8ac 100644
--- a/lib/adapters/postgres.js
+++ b/lib/adapters/postgres.js
@@ -164,6 +164,12 @@ PG.prototype.toDatabase = function (prop, val) {
         if (operator === 'between') {
             return this.toDatabase(prop, val[0]) + ' AND ' + this.toDatabase(prop, val[1]);
         }
+        if (operator === 'inq' || operator === 'nin') {
+            for (var i = 0; i < val.length; i++) {
+                val[i] = escape(val[i]);
+            }
+            return val.join(',');
+        }
     }
     if (prop.type.name === 'Number') {
       if (!val && val!=0) {
@@ -239,6 +245,10 @@ PG.prototype.toFilter = function (model, filter) {
                 } else if (conds[key].constructor.name === 'Object') {
                     var condType = Object.keys(conds[key])[0];
                     var sqlCond = '"' + key + '"';
+                    if ((condType == 'inq' || condType == 'nin') && filterValue.length == 0) {
+                        fields.push(condType == 'inq' ? 'FALSE' : 'TRUE');
+                        return true;
+                    }
                     switch (condType) {
                         case 'gt':
                             sqlCond += ' > ';
diff --git a/test/common_test.js b/test/common_test.js
index 9d654368..053ea3be 100644
--- a/test/common_test.js
+++ b/test/common_test.js
@@ -711,6 +711,82 @@ function testOrm(schema) {
         }
     });
 
+
+    if (
+        schema.name === 'mysql' ||
+        schema.name === 'postgres'
+    )
+    it('should allow IN or NOT IN', function (test) {
+        User.destroyAll(function () {
+            User.create({name: 'User A', age: 21}, done);
+            User.create({name: 'User B', age: 22}, done);
+            User.create({name: 'User C', age: 23}, done);
+            User.create({name: 'User D', age: 24}, done);
+            User.create({name: 'User E', age: 25}, done);
+        });
+
+        var users = 5;
+        function done() {
+            if (--users === 0) makeTest();
+        }
+
+        function makeTest() {
+            // IN with empty array should return nothing
+            User.all({where: {name: {inq: []}}}, function (err, users) {
+                test.equal(users.length, 0, 'IN with empty array returns nothing');
+                ok();
+            });
+
+            // NOT IN with empty array should return everything
+            User.all({where: {name: {nin: []}}}, function (err, users) {
+                test.equal(users.length, 5, 'NOT IN with empty array returns everything');
+                ok();
+            });
+
+            // IN [User A] returns user with name = User A
+            User.all({where: {name: {inq: ['User A']}}}, function (err, users) {
+                test.equal(users.length, 1, 'IN searching one existing value returns 1 user');
+                test.equal(users[0].name, 'User A', 'IN [User A] returns user with name = User A');
+                ok();
+            });
+
+            // NOT IN [User A] returns users with name != User A
+            User.all({where: {name: {nin: ['User A']}}}, function (err, users) {
+                test.equal(users.length, 4, 'IN [User A] returns users with name != User A');
+                ok();
+            });
+
+            // IN [User A, User B] returns users with name = User A OR name = User B
+            User.all({where: {name: {inq: ['User A', 'User B']}}}, function (err, users) {
+                test.equal(users.length, 2, 'IN searching two existing values returns 2 users');
+                ok();
+            });
+
+            // NOT IN [User A, User B] returns users with name != User A AND name != User B
+            User.all({where: {name: {nin: ['User A', 'User B']}}}, function (err, users) {
+                test.equal(users.length, 3, 'NOT IN searching two existing values returns users with name != User A AND name != User B');
+                ok();
+            });
+
+            // IN works with numbers too
+            User.all({where: {age: {inq: [21, 22]}}}, function (err, users) {
+                test.equal(users.length, 2, 'IN works with numbers too');
+                ok();
+            });
+
+            // NOT IN works with numbers too
+            User.all({where: {age: {nin: [21, 22]}}}, function (err, users) {
+                test.equal(users.length, 3, 'NOT IN works with numbers too');
+                ok();
+            });
+        }
+
+        var tests = 8;
+        function ok() {
+            if (--tests === 0) test.done();
+        }
+    });
+
     it('should handle order clause with direction', function (test) {
         var wait = 0;
         var emails = [