diff --git a/src/database/postgres/sets.js b/src/database/postgres/sets.js
index 615cb6ad42..d0c41e6233 100644
--- a/src/database/postgres/sets.js
+++ b/src/database/postgres/sets.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var async = require('async');
+var _ = require('lodash');
 
 module.exports = function (db, module) {
 	var helpers = module.helpers.postgres;
@@ -44,9 +45,7 @@ SELECT $1::TEXT, m
 			value = [value];
 		}
 
-		keys = keys.filter(function (k, i, a) {
-			return a.indexOf(k) === i;
-		});
+		keys = _.uniq(keys);
 
 		module.transaction(function (tx, done) {
 			var query = tx.client.query.bind(tx.client);
diff --git a/src/meta/build.js b/src/meta/build.js
index c5fc937d30..224f22d508 100644
--- a/src/meta/build.js
+++ b/src/meta/build.js
@@ -167,19 +167,14 @@ function build(targets, options, callback) {
 			return aliases[target];
 		})
 		// filter nonexistent targets
-		.filter(Boolean)
-		// map multitargets to their sets
-		.reduce(function (prev, target) {
-			if (Array.isArray(targetHandlers[target])) {
-				return prev.concat(targetHandlers[target]);
-			}
-
-			return prev.concat(target);
-		}, [])
-		// unique
-		.filter(function (target, i, arr) {
-			return arr.indexOf(target) === i;
-		});
+		.filter(Boolean);
+
+	// map multitargets to their sets
+	targets = _.uniq(_.flatMap(targets, target => (
+		Array.isArray(targetHandlers[target]) ?
+			targetHandlers[target] :
+			target
+	)));
 
 	winston.verbose('[build] building the following targets: ' + targets.join(', '));
 
diff --git a/src/notifications.js b/src/notifications.js
index 91fb573991..2f0f5ab916 100644
--- a/src/notifications.js
+++ b/src/notifications.js
@@ -558,11 +558,9 @@ Notifications.merge = function (notifications, callback) {
 			case 'notifications:user_posted_to':
 			case 'notifications:user_flagged_post_in':
 			case 'notifications:user_flagged_user':
-				var usernames = set.map(function (notifObj) {
+				var usernames = _.uniq(set.map(function (notifObj) {
 					return notifObj && notifObj.user && notifObj.user.username;
-				}).filter(function (username, idx, array) {
-					return array.indexOf(username) === idx;
-				});
+				}));
 				var numUsers = usernames.length;
 
 				var title = utils.decodeHTMLEntities(notifications[modifyIndex].topicTitle || '');
diff --git a/src/plugins/load.js b/src/plugins/load.js
index 903d2b46c8..3d39b24d44 100644
--- a/src/plugins/load.js
+++ b/src/plugins/load.js
@@ -81,31 +81,6 @@ module.exports = function (Plugins) {
 	}
 
 	Plugins.prepareForBuild = function (targets, callback) {
-		if (targets.includes('client js bundle')) {
-			Plugins.clientScripts.length = 0;
-		}
-
-		if (targets.includes('admin js bundle')) {
-			Plugins.acpScripts.length = 0;
-		}
-
-		if (targets.includes('client side styles') || targets.includes('admin control panel styles')) {
-			Plugins.cssFiles.length = 0;
-			Plugins.lessFiles.length = 0;
-			if (targets.includes('admin control panel styles')) {
-				Plugins.acpLessFiles.length = 0;
-			}
-		}
-
-		if (targets.includes('sounds')) {
-			Plugins.soundpacks.length = 0;
-		}
-
-		if (targets.includes('languages')) {
-			Plugins.languageData.languages = [];
-			Plugins.languageData.namespaces = [];
-		}
-
 		var map = {
 			'plugin static dirs': ['staticDirs'],
 			'requirejs modules': ['modules'],
@@ -117,13 +92,27 @@ module.exports = function (Plugins) {
 			languages: ['languageData'],
 		};
 
-		var fields = targets.reduce(function (prev, target) {
-			if (!map[target]) {
-				return prev;
+		var fields = _.uniq(_.flatMap(targets, target => map[target] || []));
+
+		// clear old data before build
+		fields.forEach((field) => {
+			switch (field) {
+			case 'clientScripts':
+			case 'acpScripts':
+			case 'cssFiles':
+			case 'lessFiles':
+			case 'acpLessFiles':
+				Plugins[field].length = 0;
+				break;
+			case 'soundpack':
+				Plugins.soundpacks.length = 0;
+				break;
+			case 'languageData':
+				Plugins.languageData.languages = [];
+				Plugins.languageData.namespaces = [];
+				break;
+			// do nothing for modules and staticDirs
 			}
-			return prev.concat(map[target]);
-		}, []).filter(function (field, i, arr) {
-			return arr.indexOf(field) === i;
 		});
 
 		winston.verbose('[plugins] loading the following fields from plugin data: ' + fields.join(', '));