diff --git a/README.md b/README.md
index 4a3afe2..2209ed5 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,7 @@ Currently supported commands:
 - SETEX
 - SETNX
 - GET
+- MSET
 
 Installation:
 ```
@@ -66,7 +67,7 @@ Default `GzipCompressor` uses [`gzencode`](http://php.net/gzencode) php function
 You can create your own compressor by implementing `CompressorInterface`.
 
 Roadmap:
-- Add more commands (`MSET`, `HSET` and their get counterparts at least)
+- Add more commands (`HSET` and their get counterparts at least)
 - Make initialization simpler
 
 [ico-license]: https://img.shields.io/github/license/b1rdex/predis-compressible.svg?style=flat-square
diff --git a/src/Command/StringSetMultiple.php b/src/Command/StringSetMultiple.php
index ddabe14..0be6b3a 100644
--- a/src/Command/StringSetMultiple.php
+++ b/src/Command/StringSetMultiple.php
@@ -13,7 +13,7 @@ class StringSetMultiple extends BaseStringSetMultiple implements ArgumentsCompre
 
     public function compressArguments(array $arguments): array
     {
-        for ($i = 0, $count = \count($arguments); $i < $count; $i += 2) {
+        for ($i = 1, $count = \count($arguments); $i < $count; $i += 2) {
             $this->compressArgument($arguments, $i);
         }
 
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 11f32dd..fa69161 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -8,6 +8,7 @@
 use B1rdex\PredisCompressible\Command\StringGetMultiple;
 use B1rdex\PredisCompressible\Command\StringSet;
 use B1rdex\PredisCompressible\Command\StringSetExpire;
+use B1rdex\PredisCompressible\Command\StringSetMultiple;
 use B1rdex\PredisCompressible\Command\StringSetPreserve;
 use B1rdex\PredisCompressible\Compressor\ConditionalCompressorWrapper;
 use B1rdex\PredisCompressible\Compressor\GzipCompressor;
@@ -66,6 +67,7 @@ private function getCompressedClient(): Client
                     $profile->defineCommand('SETNX', StringSetPreserve::class);
                     $profile->defineCommand('GET', StringGet::class);
                     $profile->defineCommand('MGET', StringGetMultiple::class);
+                    $profile->defineCommand('MSET', StringSetMultiple::class);
                 }
 
                 return $profile;
@@ -190,7 +192,8 @@ public function it_should_allow_mset(): void
         $value1 = 'value compressed1';
         $value2 = 'value compressed2';
         $value3 = 'value compressed3';
-        $sut->mset([$key1, $value1, $key2, $value2, $key3, $value3]);
+        $sut->mset([$key1 => $value1, $key2 => $value2, $key3 => $value3]);
         self::assertSame([$value1, $value2, $value3], $sut->mget([$key1, $key2, $key3]));
+        self::assertNotSame([$value1, $value2, $value3], $this->getOriginalClient()->mget([$key1, $key2, $key3]));
     }
 }