diff --git a/composer.json b/composer.json
index 84db042..82b359c 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,5 @@
 {
     "name": "microsoft/azure-storage-common",
-    "version": "1.5.2",
     "description": "This project provides a set of common code shared by Azure Storage Blob, Table, Queue and File PHP client libraries.",
     "keywords": [ "php", "azure", "storage", "sdk", "common" ],
     "license": "MIT",
diff --git a/src/Common/Internal/Middlewares/CommonRequestMiddleware.php b/src/Common/Internal/Middlewares/CommonRequestMiddleware.php
index 4da9ba0..76dcc25 100644
--- a/src/Common/Internal/Middlewares/CommonRequestMiddleware.php
+++ b/src/Common/Internal/Middlewares/CommonRequestMiddleware.php
@@ -60,9 +60,9 @@ class CommonRequestMiddleware extends MiddlewareBase
      * @param array       $headers              The headers to be added.
      */
     public function __construct(
-        IAuthScheme $authenticationScheme = null,
-        $storageAPIVersion,
-        $serviceSDKVersion,
+        ?IAuthScheme $authenticationScheme = null,
+        ?string $storageAPIVersion = null,
+        ?string $serviceSDKVersion = null,
         array $headers = array()
     ) {
         $this->authenticationScheme = $authenticationScheme;
diff --git a/src/Common/Internal/RestProxy.php b/src/Common/Internal/RestProxy.php
index c00bafc..e765c64 100644
--- a/src/Common/Internal/RestProxy.php
+++ b/src/Common/Internal/RestProxy.php
@@ -54,7 +54,7 @@ class RestProxy
      *
      * @param Serialization\ISerializer $dataSerializer The data serializer.
      */
-    public function __construct(Serialization\ISerializer $dataSerializer = null)
+    public function __construct(?Serialization\ISerializer $dataSerializer = null)
     {
         $this->middlewares    = array();
         $this->dataSerializer = $dataSerializer;
diff --git a/src/Common/Internal/Serialization/ISerializer.php b/src/Common/Internal/Serialization/ISerializer.php
index 0e3a2eb..00c9815 100644
--- a/src/Common/Internal/Serialization/ISerializer.php
+++ b/src/Common/Internal/Serialization/ISerializer.php
@@ -56,7 +56,7 @@ public static function objectSerialize($targetObject, $rootName);
      *
      * @return string
      */
-    public function serialize(array $array, array $properties = null);
+    public function serialize(array $array, ?array $properties = null);
 
 
     /**
diff --git a/src/Common/Internal/Serialization/XmlSerializer.php b/src/Common/Internal/Serialization/XmlSerializer.php
index ebd1243..8ba990e 100644
--- a/src/Common/Internal/Serialization/XmlSerializer.php
+++ b/src/Common/Internal/Serialization/XmlSerializer.php
@@ -54,7 +54,7 @@ class XmlSerializer implements ISerializer
      *
      * @return array
      */
-    private function sxml2arr($sxml, array $arr = null)
+    private function sxml2arr($sxml, ?array $arr = null)
     {
         foreach ((array) $sxml as $key => $value) {
             if (is_object($value) || (is_array($value))) {
@@ -77,7 +77,7 @@ private function sxml2arr($sxml, array $arr = null)
      *
      * @return void
      */
-    private function arr2xml(\XMLWriter $xmlw, array $data, $defaultTag = null)
+    private function arr2xml(\XMLWriter $xmlw, array $data, ?string $defaultTag = null)
     {
         foreach ($data as $key => $value) {
             if ($key === Resources::XTAG_ATTRIBUTES) {
@@ -190,7 +190,7 @@ public static function objectSerialize($targetObject, $rootName)
      *
      * @return string
      */
-    public function serialize(array $array, array $properties = null)
+    public function serialize(array $array, ?array $properties = null)
     {
         $xmlVersion   = '1.0';
         $xmlEncoding  = 'UTF-8';
diff --git a/src/Common/Internal/ServiceRestProxy.php b/src/Common/Internal/ServiceRestProxy.php
index 15ef327..1d94e2b 100644
--- a/src/Common/Internal/ServiceRestProxy.php
+++ b/src/Common/Internal/ServiceRestProxy.php
@@ -349,7 +349,7 @@ protected function sendAsync(
         $path,
         $expected = Resources::STATUS_OK,
         $body = Resources::EMPTY_STRING,
-        ServiceOptions $serviceOptions = null
+        ?ServiceOptions $serviceOptions = null
     ) {
         if ($serviceOptions == null) {
             $serviceOptions = new ServiceOptions();
@@ -560,7 +560,7 @@ public static function groupQueryValues(array $values)
      *
      * @return array
      */
-    protected function addMetadataHeaders(array $headers, array $metadata = null)
+    protected function addMetadataHeaders(array $headers, ?array $metadata = null)
     {
         Utilities::validateMetadata($metadata);
 
@@ -577,7 +577,7 @@ protected function addMetadataHeaders(array $headers, array $metadata = null)
      *
      * @return array
      */
-    public function generateMetadataHeaders(array $metadata = null)
+    public function generateMetadataHeaders(?array $metadata = null)
     {
         $metadataHeaders = array();
 
diff --git a/src/Common/Internal/ServiceRestTrait.php b/src/Common/Internal/ServiceRestTrait.php
index cc4f507..91fbbd4 100644
--- a/src/Common/Internal/ServiceRestTrait.php
+++ b/src/Common/Internal/ServiceRestTrait.php
@@ -56,7 +56,7 @@ trait ServiceRestTrait
      * @see http://msdn.microsoft.com/en-us/library/windowsazure/hh452239.aspx
      */
     public function getServiceProperties(
-        ServiceOptions $options = null
+        ?ServiceOptions $options = null
     ) {
         return $this->getServicePropertiesAsync($options)->wait();
     }
@@ -71,7 +71,7 @@ public function getServiceProperties(
      * @see http://msdn.microsoft.com/en-us/library/windowsazure/hh452239.aspx
      */
     public function getServicePropertiesAsync(
-        ServiceOptions $options = null
+        ?ServiceOptions $options = null
     ) {
         $method      = Resources::HTTP_GET;
         $headers     = array();
@@ -126,7 +126,7 @@ public function getServicePropertiesAsync(
      */
     public function setServiceProperties(
         ServiceProperties $serviceProperties,
-        ServiceOptions $options = null
+        ?ServiceOptions $options = null
     ) {
         $this->setServicePropertiesAsync($serviceProperties, $options)->wait();
     }
@@ -146,7 +146,7 @@ public function setServiceProperties(
      */
     public function setServicePropertiesAsync(
         ServiceProperties $serviceProperties,
-        ServiceOptions $options = null
+        ?ServiceOptions $options = null
     ) {
         Validate::isTrue(
             $serviceProperties instanceof ServiceProperties,
@@ -202,7 +202,7 @@ public function setServicePropertiesAsync(
      *
      * @return GetServiceStatsResult
      */
-    public function getServiceStats(ServiceOptions $options = null)
+    public function getServiceStats(?ServiceOptions $options = null)
     {
         return $this->getServiceStatsAsync($options)->wait();
     }
@@ -215,7 +215,7 @@ public function getServiceStats(ServiceOptions $options = null)
      *
      * @return \GuzzleHttp\Promise\PromiseInterface
      */
-    public function getServiceStatsAsync(ServiceOptions $options = null)
+    public function getServiceStatsAsync(?ServiceOptions $options = null)
     {
         $method      = Resources::HTTP_GET;
         $headers     = array();
diff --git a/src/Common/Internal/Utilities.php b/src/Common/Internal/Utilities.php
index 5765e4f..b7b0e40 100644
--- a/src/Common/Internal/Utilities.php
+++ b/src/Common/Internal/Utilities.php
@@ -49,7 +49,7 @@ class Utilities
      *
      * @return mixed
      */
-    public static function tryGetValue($array, $key, $default = null)
+    public static function tryGetValue($array, $key, mixed $default = null)
     {
         return (!is_null($array)) && is_array($array) && array_key_exists($key, $array)
             ? $array[$key]
@@ -260,7 +260,7 @@ public static function unserialize($xml)
      *
      * @return array
      */
-    private static function _sxml2arr($sxml, array $arr = null)
+    private static function _sxml2arr($sxml, ?array $arr = null)
     {
         foreach ((array) $sxml as $key => $value) {
             if (is_object($value) || (is_array($value))) {
@@ -287,8 +287,8 @@ private static function _sxml2arr($sxml, array $arr = null)
     public static function serialize(
         array $array,
         $rootName,
-        $defaultTag = null,
-        $standalone = null
+        ?string $defaultTag = null,
+        ?string $standalone = null
     ) {
         $xmlVersion  = '1.0';
         $xmlEncoding = 'UTF-8';
@@ -323,7 +323,7 @@ public static function serialize(
     private static function _arr2xml(
         \XMLWriter $xmlw,
         array $data,
-        $defaultTag = null
+        ?string $defaultTag = null
     ) {
         foreach ($data as $key => $value) {
             if (strcmp($key, '@attributes') == 0) {
@@ -528,7 +528,7 @@ public static function arrayKeyExistsInsensitive($key, array $search)
      *
      * @return mixed
      */
-    public static function tryGetValueInsensitive($key, $haystack, $default = null)
+    public static function tryGetValueInsensitive($key, $haystack,mixed $default = null)
     {
         $array = array_change_key_case($haystack);
         return Utilities::tryGetValue($array, strtolower($key), $default);
@@ -751,7 +751,7 @@ public static function getMetadataArray(array $headers)
      *
      * @return void
      */
-    public static function validateMetadata(array $metadata = null)
+    public static function validateMetadata(?array $metadata = null)
     {
         if (!is_null($metadata)) {
             Validate::isArray($metadata, 'metadata');
diff --git a/src/Common/Models/ServiceOptions.php b/src/Common/Models/ServiceOptions.php
index 5825a42..6e597f0 100644
--- a/src/Common/Models/ServiceOptions.php
+++ b/src/Common/Models/ServiceOptions.php
@@ -88,7 +88,7 @@ class ServiceOptions
     /**
      * Initialize the properties to default value.
      */
-    public function __construct(ServiceOptions $options = null)
+    public function __construct(?ServiceOptions $options = null)
     {
         if ($options == null) {
             $this->setNumberOfConcurrency(Resources::NUMBER_OF_CONCURRENCY);