diff --git a/.eslintrc b/.eslintrc
index bbba3aa94e..4f7d4e2413 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -54,9 +54,9 @@
 		"no-restricted-syntax": "off",
 		"no-script-url": "off",
 		"default-case": "off",
+		"linebreak-style": "off",
 
 		// "no-multi-assign": "off",
-		// "linebreak-style": "off",
 		// "one-var": "off",
 		// "no-undef": "off",
 		// "max-nested-callbacks": "off",
diff --git a/src/database/mongo/sorted.js b/src/database/mongo/sorted.js
index 59bd05b9fd..4168199bb5 100644
--- a/src/database/mongo/sorted.js
+++ b/src/database/mongo/sorted.js
@@ -241,7 +241,7 @@ module.exports = function (db, module) {
 
 	module.sortedSetScore = function (key, value, callback) {
 		if (!key) {
-			return callback();
+			return callback(null, null);
 		}
 		value = helpers.valueToString(value);
 		db.collection('objects').findOne({ _key: key, value: value }, { fields: { _id: 0, score: 1 } }, function (err, result) {
@@ -274,7 +274,7 @@ module.exports = function (db, module) {
 
 	module.sortedSetScores = function (key, values, callback) {
 		if (!key) {
-			return callback();
+			return callback(null, null);
 		}
 		values = values.map(helpers.valueToString);
 		db.collection('objects').find({ _key: key, value: { $in: values } }, { _id: 0, value: 1, score: 1 }).toArray(function (err, result) {
diff --git a/src/database/redis/helpers.js b/src/database/redis/helpers.js
index 7100437177..b1c2a98092 100644
--- a/src/database/redis/helpers.js
+++ b/src/database/redis/helpers.js
@@ -1,6 +1,6 @@
 'use strict';
 
-var helpers = {};
+var helpers = module.exports;
 
 helpers.multiKeys = function (redisClient, command, keys, callback) {
 	callback = callback || function () {};
@@ -15,7 +15,7 @@ helpers.multiKeysValue = function (redisClient, command, keys, value, callback)
 	callback = callback || function () {};
 	var multi = redisClient.multi();
 	for (var i = 0; i < keys.length; i += 1) {
-		multi[command](keys[i], value);
+		multi[command](String(keys[i]), String(value));
 	}
 	multi.exec(callback);
 };
@@ -24,7 +24,7 @@ helpers.multiKeyValues = function (redisClient, command, key, values, callback)
 	callback = callback || function () {};
 	var multi = redisClient.multi();
 	for (var i = 0; i < values.length; i += 1) {
-		multi[command](key, values[i]);
+		multi[command](String(key), String(values[i]));
 	}
 	multi.exec(callback);
 };
@@ -35,5 +35,3 @@ helpers.resultsToBool = function (results) {
 	}
 	return results;
 };
-
-module.exports = helpers;
diff --git a/src/database/redis/sorted.js b/src/database/redis/sorted.js
index 67f55bf343..9bb004550a 100644
--- a/src/database/redis/sorted.js
+++ b/src/database/redis/sorted.js
@@ -124,8 +124,12 @@ module.exports = function (redisClient, module) {
 	};
 
 	module.sortedSetScore = function (key, value, callback) {
+		if (!key || value === undefined) {
+			return callback(null, null);
+		}
+
 		redisClient.zscore(key, value, function (err, score) {
-			callback(err, !err ? parseFloat(score) : undefined);
+			callback(err, !err ? parseFloat(score) : null);
 		});
 	};
 
diff --git a/test/database/sorted.js b/test/database/sorted.js
index 939f4b259e..b90e9cf71f 100644
--- a/test/database/sorted.js
+++ b/test/database/sorted.js
@@ -324,6 +324,22 @@ describe('Sorted Set methods', function () {
 				done();
 			});
 		});
+
+		it('should not error if key is undefined', function (done) {
+			db.sortedSetScore(undefined, 1, function (err, score) {
+				assert.ifError(err);
+				assert.strictEqual(score, null);
+				done();
+			});
+		});
+
+		it('should not error if value is undefined', function (done) {
+			db.sortedSetScore('sortedSetTest1', undefined, function (err, score) {
+				assert.ifError(err);
+				assert.strictEqual(score, null);
+				done();
+			});
+		});
 	});
 
 	describe('sortedSetsScore()', function () {
@@ -335,6 +351,15 @@ describe('Sorted Set methods', function () {
 				done();
 			});
 		});
+
+		it('should return scores even if some keys are undefined', function (done) {
+			db.sortedSetsScore(['sortedSetTest1', undefined, 'doesnotexist'], 'value1', function (err, scores) {
+				assert.equal(err, null);
+				assert.equal(arguments.length, 2);
+				assert.deepEqual(scores, [1.1, null, null]);
+				done();
+			});
+		});
 	});
 
 	describe('sortedSetScores()', function () {
@@ -358,6 +383,15 @@ describe('Sorted Set methods', function () {
 				done();
 			});
 		});
+
+		it('should return scores even if some values are undefined', function (done) {
+			db.sortedSetScores('sortedSetTest1', ['value2', undefined, 'doesnotexist'], function (err, scores) {
+				assert.equal(err, null);
+				assert.equal(arguments.length, 2);
+				assert.deepEqual(scores, [1.2, null, null]);
+				done();
+			});
+		});
 	});
 
 	describe('isSortedSetMember()', function () {