diff --git a/lib/data-types.js b/lib/data-types.js
index 66ab5b9af0ee..371652be60f9 100644
--- a/lib/data-types.js
+++ b/lib/data-types.js
@@ -469,7 +469,9 @@ class DATE extends ABSTRACT {
     return momentTz(date);
   }
   _stringify(date, options) {
-    date = this._applyTimezone(date, options);
+    if (!moment.isMoment(date)) {
+      date = this._applyTimezone(date, options);
+    }
     // Z here means current timezone, _not_ UTC
     return date.format('YYYY-MM-DD HH:mm:ss.SSS Z');
   }
diff --git a/lib/dialects/db2/data-types.js b/lib/dialects/db2/data-types.js
index b2855b694634..a908a9498e30 100644
--- a/lib/dialects/db2/data-types.js
+++ b/lib/dialects/db2/data-types.js
@@ -1,6 +1,7 @@
 'use strict';
 
-const moment = require('moment-timezone');
+const momentTz = require('moment-timezone');
+const moment = require('moment');
 
 module.exports = BaseTypes => {
   const warn = BaseTypes.ABSTRACT.warn.bind(undefined,
@@ -194,7 +195,10 @@ module.exports = BaseTypes => {
       return `TIMESTAMP${ this._length ? `(${ this._length })` : ''}`;
     }
     _stringify(date, options) {
-      date = this._applyTimezone(date, options);
+      if (!moment.isMoment(date)) {
+        date = this._applyTimezone(date, options);
+      }
+
       if (this._length > 0) {
         let msec = '.';
         for ( let i = 0; i < this._length && i < 6; i++ ) {
@@ -211,14 +215,14 @@ module.exports = BaseTypes => {
       if (value === null) {
         return value;
       }
-      value = new Date(moment.utc(value));
+      value = new Date(momentTz.utc(value));
       return value;
     }
   }
 
   class DATEONLY extends BaseTypes.DATEONLY {
     static parse(value) {
-      return moment(value).format('YYYY-MM-DD');
+      return momentTz(value).format('YYYY-MM-DD');
     }
   }
 
diff --git a/lib/dialects/mariadb/data-types.js b/lib/dialects/mariadb/data-types.js
index c163f206701f..202ebe5868b7 100644
--- a/lib/dialects/mariadb/data-types.js
+++ b/lib/dialects/mariadb/data-types.js
@@ -2,7 +2,8 @@
 
 const wkx = require('wkx');
 const _ = require('lodash');
-const moment = require('moment-timezone');
+const momentTz = require('moment-timezone');
+const moment = require('moment');
 
 module.exports = BaseTypes => {
   BaseTypes.ABSTRACT.prototype.dialectTypes = 'https://mariadb.com/kb/en/library/resultset/#field-types';
@@ -54,20 +55,19 @@ module.exports = BaseTypes => {
       return this._length ? `DATETIME(${this._length})` : 'DATETIME';
     }
     _stringify(date, options) {
-      if (_.isDate(date)) {
+      if (!moment.isMoment(date)) {
         date = this._applyTimezone(date, options);
-        return date.format('YYYY-MM-DD HH:mm:ss.SSS');
       }
 
-      return date;
+      return date.format('YYYY-MM-DD HH:mm:ss.SSS');
     }
     static parse(value, options) {
       value = value.string();
       if (value === null) {
         return value;
       }
-      if (moment.tz.zone(options.timezone)) {
-        value = moment.tz(value, options.timezone).toDate();
+      if (momentTz.tz.zone(options.timezone)) {
+        value = momentTz.tz(value, options.timezone).toDate();
       }
       else {
         value = new Date(`${value} ${options.timezone}`);
diff --git a/lib/dialects/mysql/data-types.js b/lib/dialects/mysql/data-types.js
index 017b74c130dd..3190c695ccc0 100644
--- a/lib/dialects/mysql/data-types.js
+++ b/lib/dialects/mysql/data-types.js
@@ -2,7 +2,9 @@
 
 const wkx = require('wkx');
 const _ = require('lodash');
-const moment = require('moment-timezone');
+const momentTz = require('moment-timezone');
+const moment = require('moment');
+
 module.exports = BaseTypes => {
   BaseTypes.ABSTRACT.prototype.dialectTypes = 'https://dev.mysql.com/doc/refman/5.7/en/data-types.html';
 
@@ -53,24 +55,22 @@ module.exports = BaseTypes => {
       return this._length ? `DATETIME(${this._length})` : 'DATETIME';
     }
     _stringify(date, options) {
-      if (_.isDate(date)) {
+      if (!moment.isMoment(date)) {
         date = this._applyTimezone(date, options);
-        // Fractional DATETIMEs only supported on MySQL 5.6.4+
-        if (this._length) {
-          return date.format('YYYY-MM-DD HH:mm:ss.SSS');
-        }
-        return date.format('YYYY-MM-DD HH:mm:ss');
       }
-
-      return date;
+      // Fractional DATETIMEs only supported on MySQL 5.6.4+
+      if (this._length) {
+        return date.format('YYYY-MM-DD HH:mm:ss.SSS');
+      }
+      return date.format('YYYY-MM-DD HH:mm:ss');
     }
     static parse(value, options) {
       value = value.string();
       if (value === null) {
         return value;
       }
-      if (moment.tz.zone(options.timezone)) {
-        value = moment.tz(value, options.timezone).toDate();
+      if (momentTz.tz.zone(options.timezone)) {
+        value = momentTz.tz(value, options.timezone).toDate();
       }
       else {
         value = new Date(`${value} ${options.timezone}`);
diff --git a/lib/dialects/postgres/connection-manager.js b/lib/dialects/postgres/connection-manager.js
index 2d12b11176fa..f60b67df9d4e 100644
--- a/lib/dialects/postgres/connection-manager.js
+++ b/lib/dialects/postgres/connection-manager.js
@@ -7,7 +7,7 @@ const debug = logger.debugContext('connection:pg');
 const sequelizeErrors = require('../../errors');
 const semver = require('semver');
 const dataTypes = require('../../data-types');
-const moment = require('moment-timezone');
+const momentTz = require('moment-timezone');
 const { promisify } = require('util');
 
 class ConnectionManager extends AbstractConnectionManager {
@@ -224,7 +224,7 @@ class ConnectionManager extends AbstractConnectionManager {
     }
 
     if (!this.sequelize.config.keepDefaultTimezone) {
-      const isZone = !!moment.tz.zone(this.sequelize.options.timezone);
+      const isZone = !!momentTz.tz.zone(this.sequelize.options.timezone);
       if (isZone) {
         query += `SET TIME ZONE '${this.sequelize.options.timezone}';`;
       } else {
diff --git a/lib/dialects/snowflake/data-types.js b/lib/dialects/snowflake/data-types.js
index 8d424d0abde2..0cfe20a33c4d 100644
--- a/lib/dialects/snowflake/data-types.js
+++ b/lib/dialects/snowflake/data-types.js
@@ -1,6 +1,8 @@
 'use strict';
 
-const moment = require('moment-timezone');
+const momentTz = require('moment-timezone');
+const moment = require('moment');
+
 module.exports = BaseTypes => {
   BaseTypes.ABSTRACT.prototype.dialectTypes = 'https://dev.snowflake.com/doc/refman/5.7/en/data-types.html';
 
@@ -40,7 +42,9 @@ module.exports = BaseTypes => {
       return 'TIMESTAMP';
     }
     _stringify(date, options) {
-      date = this._applyTimezone(date, options);
+      if (!moment.isMoment(date)) {
+        date = this._applyTimezone(date, options);
+      }
       if (this._length) {
         return date.format('YYYY-MM-DD HH:mm:ss.SSS');
       }
@@ -51,8 +55,8 @@ module.exports = BaseTypes => {
       if (value === null) {
         return value;
       }
-      if (moment.tz.zone(options.timezone)) {
-        value = moment.tz(value, options.timezone).toDate();
+      if (momentTz.tz.zone(options.timezone)) {
+        value = momentTz.tz(value, options.timezone).toDate();
       }
       else {
         value = new Date(`${value} ${options.timezone}`);
diff --git a/test/integration/model/findAll.test.js b/test/integration/model/findAll.test.js
index eae031ed1384..48f3035d3052 100644
--- a/test/integration/model/findAll.test.js
+++ b/test/integration/model/findAll.test.js
@@ -387,6 +387,19 @@ describe(Support.getTestDialectTeaser('Model'), () => {
         expect(users[0].intVal).to.equal(10);
       });
 
+      it('should be able to find a row using greater than or equal to logic with moment dates', async function() {
+        const users = await this.User.findAll({
+          where: {
+            theDate: {
+              [Op.gte]: moment('2013-01-09')
+            }
+          }
+        });
+
+        expect(users[0].username).to.equal('boo2');
+        expect(users[0].intVal).to.equal(10);
+      });
+
       it('should be able to find a row using greater than or equal to', async function() {
         const user = await this.User.findOne({
           where: {