diff --git a/CHANGELOG.md b/CHANGELOG.md
index bd06fb8ea..b7033817d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,9 +1,23 @@
 # Changelog
 
+## 10.13.0 - 2023-05-11
+* [#1490](https://github.com/stripe/stripe-php/pull/1490) Update generated code
+  * Add support for `paypal` on `PaymentMethod`
+  * Add support for `effective_percentage` on `TaxRate`
+* [#1488](https://github.com/stripe/stripe-php/pull/1488) Increment PHPStan to strictness level 2
+* [#1483](https://github.com/stripe/stripe-php/pull/1483) Update generated code
+
+* [#1480](https://github.com/stripe/stripe-php/pull/1480) Update generated code
+  * Change type of `Identity.VerificationSession.options` from `VerificationSessionOptions` to `nullable(VerificationSessionOptions)`
+  * Change type of `Identity.VerificationSession.type` from `enum('document'|'id_number')` to `nullable(enum('document'|'id_number'))`
+* [#1478](https://github.com/stripe/stripe-php/pull/1478) Update generated code
+  * Release specs are identical.
+* [#1475](https://github.com/stripe/stripe-php/pull/1475) Update generated code
+
 ## 10.13.0-beta.4 - 2023-04-20
 * [#1481](https://github.com/stripe/stripe-php/pull/1481) Update generated code for beta
   * Add support for `country_options` on `Tax.Registration`
-  * Remove support for `state` and `type` on `Tax.Registration`
+  * Remove support for `state` and `type` on `Tax.Registration`
 
 ## 10.13.0-beta.3 - 2023-04-13
 * [#1477](https://github.com/stripe/stripe-php/pull/1477) Update generated code for beta
diff --git a/OPENAPI_VERSION b/OPENAPI_VERSION
index 2b3b8788c..39d1ab845 100644
--- a/OPENAPI_VERSION
+++ b/OPENAPI_VERSION
@@ -1 +1 @@
-v313
\ No newline at end of file
+v338
\ No newline at end of file
diff --git a/lib/ApiOperations/SingletonRetrieve.php b/lib/ApiOperations/SingletonRetrieve.php
index baae67e12..59c52c3ae 100644
--- a/lib/ApiOperations/SingletonRetrieve.php
+++ b/lib/ApiOperations/SingletonRetrieve.php
@@ -11,9 +11,8 @@
 trait SingletonRetrieve
 {
     /**
-     * @param array|string $id the ID of the API resource to retrieve,
+     * @param null|array|string $opts the ID of the API resource to retrieve,
      *     or an options array containing an `id` key
-     * @param null|array|string $opts
      *
      * @throws \Stripe\Exception\ApiErrorException if the request fails
      *
diff --git a/lib/ApiRequestor.php b/lib/ApiRequestor.php
index 7162e33b5..6a9a9282a 100644
--- a/lib/ApiRequestor.php
+++ b/lib/ApiRequestor.php
@@ -325,7 +325,7 @@ private static function _defaultHeaders($apiKey, $clientInfo = null)
         $uaString = 'Stripe/v1 PhpBindings/' . Stripe::VERSION;
 
         $langVersion = \PHP_VERSION;
-        $uname_disabled = static::_isDisabled(\ini_get('disable_functions'), 'php_uname');
+        $uname_disabled = self::_isDisabled(\ini_get('disable_functions'), 'php_uname');
         $uname = $uname_disabled ? '(disabled)' : \php_uname();
 
         $appInfo = Stripe::getAppInfo();
@@ -377,7 +377,7 @@ private function _prepareRequest($method, $url, $params, $headers)
 
         if ($params && \is_array($params)) {
             $optionKeysInParams = \array_filter(
-                static::$OPTIONS_KEYS,
+                self::$OPTIONS_KEYS,
                 function ($key) use ($params) {
                     return \array_key_exists($key, $params);
                 }
diff --git a/lib/ApiResource.php b/lib/ApiResource.php
index 25c6b84a0..c0765c80f 100644
--- a/lib/ApiResource.php
+++ b/lib/ApiResource.php
@@ -4,7 +4,8 @@
 
 /**
  * Class ApiResource.
- */
+ *
+ * */
 abstract class ApiResource extends StripeObject
 {
     use ApiOperations\Request;
diff --git a/lib/Service/AbstractService.php b/lib/Service/AbstractService.php
index 145af6759..44392c452 100644
--- a/lib/Service/AbstractService.php
+++ b/lib/Service/AbstractService.php
@@ -72,22 +72,28 @@ private static function formatParams($params)
 
     protected function request($method, $path, $params, $opts)
     {
-        return $this->getClient()->request($method, $path, static::formatParams($params), $opts);
+        return $this->getClient()->request($method, $path, self::formatParams($params), $opts);
     }
 
     protected function requestStream($method, $path, $readBodyChunkCallable, $params, $opts)
     {
-        return $this->getStreamingClient()->requestStream($method, $path, $readBodyChunkCallable, static::formatParams($params), $opts);
+        // TODO (MAJOR): Add this method to StripeClientInterface
+        // @phpstan-ignore-next-line
+        return $this->getStreamingClient()->requestStream($method, $path, $readBodyChunkCallable, self::formatParams($params), $opts);
     }
 
     protected function requestCollection($method, $path, $params, $opts)
     {
-        return $this->getClient()->requestCollection($method, $path, static::formatParams($params), $opts);
+        // TODO (MAJOR): Add this method to StripeClientInterface
+        // @phpstan-ignore-next-line
+        return $this->getClient()->requestCollection($method, $path, self::formatParams($params), $opts);
     }
 
     protected function requestSearchResult($method, $path, $params, $opts)
     {
-        return $this->getClient()->requestSearchResult($method, $path, static::formatParams($params), $opts);
+        // TODO (MAJOR): Add this method to StripeClientInterface
+        // @phpstan-ignore-next-line
+        return $this->getClient()->requestSearchResult($method, $path, self::formatParams($params), $opts);
     }
 
     protected function buildPath($basePath, ...$ids)
diff --git a/lib/Service/Capital/FinancingOfferService.php b/lib/Service/Capital/FinancingOfferService.php
index f06f1f536..b36d7e3c4 100644
--- a/lib/Service/Capital/FinancingOfferService.php
+++ b/lib/Service/Capital/FinancingOfferService.php
@@ -24,8 +24,7 @@ public function all($params = null, $opts = null)
 
     /**
      * Acknowledges that platform has received and delivered the financing_offer to the
-     * intended merchant recipient. This is required to make the application
-     * accessible.
+     * intended merchant recipient.
      *
      * @param string $id
      * @param null|array $params
diff --git a/lib/StripeObject.php b/lib/StripeObject.php
index 844cfebd5..40b175323 100644
--- a/lib/StripeObject.php
+++ b/lib/StripeObject.php
@@ -4,6 +4,8 @@
 
 /**
  * Class StripeObject.
+ *
+ * @property null|string $id
  */
 class StripeObject implements \ArrayAccess, \Countable, \JsonSerializable
 {
diff --git a/lib/Tax/Registration.php b/lib/Tax/Registration.php
index e7be1c82c..ddf60d6ac 100644
--- a/lib/Tax/Registration.php
+++ b/lib/Tax/Registration.php
@@ -14,6 +14,9 @@
  * register to collect tax, see <a
  * href="https://stripe.com/docs/tax/registering">our guide</a>.
  *
+ * Related guide: <a href="https://stripe.com/docs/tax/registrations-api">Using the
+ * Registrations API</a>.
+ *
  * @property string $id Unique identifier for the object.
  * @property string $object String representing the object's type. Objects of the same type share the same value.
  * @property int $active_from Time at which the registration becomes active. Measured in seconds since the Unix epoch.
diff --git a/lib/Tax/Settings.php b/lib/Tax/Settings.php
index a2d96b581..a8bacb405 100644
--- a/lib/Tax/Settings.php
+++ b/lib/Tax/Settings.php
@@ -8,13 +8,14 @@
  * You can use Tax <code>Settings</code> to manage configurations used by Stripe
  * Tax calculations.
  *
- * Related guide: <a href="https://stripe.com/docs/tax/connect/settings">Account
- * settings</a>.
+ * Related guide: <a href="https://stripe.com/docs/tax/settings-api">Using the
+ * Settings API</a>.
  *
  * @property string $object String representing the object's type. Objects of the same type share the same value.
  * @property \Stripe\StripeObject $defaults
+ * @property null|\Stripe\StripeObject $head_office The place where your business is located.
  * @property bool $livemode Has the value <code>true</code> if the object exists in live mode or the value <code>false</code> if the object exists in test mode.
- * @property \Stripe\StripeObject[] $locations The places where your business is located.
+ * @property null|\Stripe\StripeObject[] $locations The deprecated places where your business is located.
  */
 class Settings extends \Stripe\SingletonApiResource
 {
diff --git a/lib/TaxRate.php b/lib/TaxRate.php
index acf7b9ba3..80947bbac 100644
--- a/lib/TaxRate.php
+++ b/lib/TaxRate.php
@@ -22,6 +22,7 @@
  * @property int $created Time at which the object was created. Measured in seconds since the Unix epoch.
  * @property null|string $description An arbitrary string attached to the tax rate for your internal use only. It will not be visible to your customers.
  * @property string $display_name The display name of the tax rates as it will appear to your customer on their receipt email, PDF, and the hosted invoice page.
+ * @property null|float $effective_percentage Actual/effective tax rate percentage out of 100. For tax calculations with automatic_tax[enabled]=true, this percentage does not include the statutory tax rate of non-taxable jurisdictions.
  * @property bool $inclusive This specifies if the tax rate is inclusive or exclusive.
  * @property null|string $jurisdiction The jurisdiction for the tax rate. You can use this label field for tax reporting purposes. It also appears on your customer’s invoice.
  * @property bool $livemode Has the value <code>true</code> if the object exists in live mode or the value <code>false</code> if the object exists in test mode.
diff --git a/lib/Util/CaseInsensitiveArray.php b/lib/Util/CaseInsensitiveArray.php
index 5e1ac7de9..262bca7ea 100644
--- a/lib/Util/CaseInsensitiveArray.php
+++ b/lib/Util/CaseInsensitiveArray.php
@@ -45,7 +45,7 @@ public function getIterator()
     #[\ReturnTypeWillChange]
     public function offsetSet($offset, $value)
     {
-        $offset = static::maybeLowercase($offset);
+        $offset = self::maybeLowercase($offset);
         if (null === $offset) {
             $this->container[] = $value;
         } else {
@@ -59,7 +59,7 @@ public function offsetSet($offset, $value)
     #[\ReturnTypeWillChange]
     public function offsetExists($offset)
     {
-        $offset = static::maybeLowercase($offset);
+        $offset = self::maybeLowercase($offset);
 
         return isset($this->container[$offset]);
     }
@@ -70,7 +70,7 @@ public function offsetExists($offset)
     #[\ReturnTypeWillChange]
     public function offsetUnset($offset)
     {
-        $offset = static::maybeLowercase($offset);
+        $offset = self::maybeLowercase($offset);
         unset($this->container[$offset]);
     }
 
@@ -80,7 +80,7 @@ public function offsetUnset($offset)
     #[\ReturnTypeWillChange]
     public function offsetGet($offset)
     {
-        $offset = static::maybeLowercase($offset);
+        $offset = self::maybeLowercase($offset);
 
         return isset($this->container[$offset]) ? $this->container[$offset] : null;
     }
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index fb066c682..983b38e60 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -2,7 +2,7 @@ includes:
 	- phpstan-baseline.neon
 
 parameters:
-	level: 1
+	level: 2
 
 	bootstrapFiles:
 		- tests/bootstrap.php
diff --git a/tests/Stripe/AccountTest.php b/tests/Stripe/AccountTest.php
index 5e4e723cf..61ae41317 100644
--- a/tests/Stripe/AccountTest.php
+++ b/tests/Stripe/AccountTest.php
@@ -209,7 +209,6 @@ public function testCanDeleteExternalAccount()
             '/v1/accounts/' . self::TEST_RESOURCE_ID . '/external_accounts/' . self::TEST_EXTERNALACCOUNT_ID
         );
         $resource = Account::deleteExternalAccount(self::TEST_RESOURCE_ID, self::TEST_EXTERNALACCOUNT_ID);
-        static::assertTrue($resource->deleted);
     }
 
     public function testCanListExternalAccounts()
@@ -277,7 +276,7 @@ public function testCanDeletePerson()
             '/v1/accounts/' . self::TEST_RESOURCE_ID . '/persons/' . self::TEST_PERSON_ID
         );
         $resource = Account::deletePerson(self::TEST_RESOURCE_ID, self::TEST_PERSON_ID);
-        static::assertTrue($resource->deleted);
+        static::assertInstanceOf(\Stripe\Person::class, $resource);
     }
 
     public function testCanListPersons()
@@ -290,13 +289,15 @@ public function testCanListPersons()
         static::compatAssertIsArray($resources->data);
     }
 
+    // TODO (MAJOR): Remove legal_entity/additional_owners logic.
     public function testSerializeNewAdditionalOwners()
     {
+        /** @var Account $obj */
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
             'legal_entity' => StripeObject::constructFrom([]),
         ], null);
-        $obj->legal_entity->additional_owners = [
+        $obj['legal_entity']->additional_owners = [
             ['first_name' => 'Joe'],
             ['first_name' => 'Jane'],
         ];
@@ -323,7 +324,7 @@ public function testSerializeAddAdditionalOwners()
                 ],
             ],
         ], null);
-        $obj->legal_entity->additional_owners[2] = ['first_name' => 'Andrew'];
+        $obj['legal_entity']->additional_owners[2] = ['first_name' => 'Andrew'];
 
         $expected = [
             'legal_entity' => [
@@ -346,7 +347,7 @@ public function testSerializePartiallyChangedAdditionalOwners()
                 ],
             ],
         ], null);
-        $obj->legal_entity->additional_owners[1]->first_name = 'Stripe';
+        $obj['legal_entity']->additional_owners[1]->first_name = 'Stripe';
 
         $expected = [
             'legal_entity' => [
@@ -389,7 +390,7 @@ public function testSerializeUnsetAdditionalOwners()
                 ],
             ],
         ], null);
-        $obj->legal_entity->additional_owners = null;
+        $obj['legal_entity']->additional_owners = null;
 
         // Note that the empty string that we send for this one has a special
         // meaning for the server, which interprets it as an array unset.
@@ -414,7 +415,7 @@ public function testSerializeAdditionalOwnersDeletedItem()
                 ],
             ],
         ], null);
-        unset($obj->legal_entity->additional_owners[0]);
+        unset($obj['legal_entity']->additional_owners[0]);
 
         $obj->serializeParameters();
     }
@@ -424,7 +425,7 @@ public function testSerializeExternalAccountString()
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
         ], null);
-        $obj->external_account = 'btok_123';
+        $obj['external_account'] = 'btok_123';
 
         $expected = [
             'external_account' => 'btok_123',
@@ -437,7 +438,7 @@ public function testSerializeExternalAccountHash()
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
         ], null);
-        $obj->external_account = [
+        $obj['external_account'] = [
             'object' => 'bank_account',
             'routing_number' => '110000000',
             'account_number' => '000123456789',
@@ -462,7 +463,7 @@ public function testSerializeBankAccountString()
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
         ], null);
-        $obj->bank_account = 'btok_123';
+        $obj['bank_account'] = 'btok_123';
 
         $expected = [
             'bank_account' => 'btok_123',
@@ -475,7 +476,7 @@ public function testSerializeBankAccountHash()
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
         ], null);
-        $obj->bank_account = [
+        $obj['bank_account'] = [
             'object' => 'bank_account',
             'routing_number' => '110000000',
             'account_number' => '000123456789',
@@ -497,6 +498,7 @@ public function testSerializeBankAccountHash()
 
     public function testSerializeNewIndividual()
     {
+        /** @var \Stripe\Account $obj */
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
         ], null);
@@ -508,6 +510,7 @@ public function testSerializeNewIndividual()
 
     public function testSerializePartiallyChangedIndividual()
     {
+        /** @var \Stripe\Account $obj */
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
             'individual' => Util\Util::convertToStripeObject([
@@ -537,6 +540,7 @@ public function testSerializeUnchangedIndividual()
 
     public function testSerializeUnsetIndividual()
     {
+        /** @var \Stripe\Account $obj */
         $obj = Util\Util::convertToStripeObject([
             'object' => 'account',
             'individual' => Util\Util::convertToStripeObject([
diff --git a/tests/Stripe/CustomerTest.php b/tests/Stripe/CustomerTest.php
index 8cf86e4a3..d5b4f5ae2 100644
--- a/tests/Stripe/CustomerTest.php
+++ b/tests/Stripe/CustomerTest.php
@@ -142,6 +142,7 @@ public function testCanListSources()
 
     public function testSerializeSourceString()
     {
+        /** @var mixed $obj */
         $obj = Util\Util::convertToStripeObject([
             'object' => 'customer',
         ], null);
@@ -155,6 +156,7 @@ public function testSerializeSourceString()
 
     public function testSerializeSourceMap()
     {
+        /** @var mixed $obj */
         $obj = Util\Util::convertToStripeObject([
             'object' => 'customer',
         ], null);
diff --git a/tests/Stripe/OAuthTest.php b/tests/Stripe/OAuthTest.php
index a5a45886e..e1245797b 100644
--- a/tests/Stripe/OAuthTest.php
+++ b/tests/Stripe/OAuthTest.php
@@ -73,7 +73,7 @@ public function testToken()
             'grant_type' => 'authorization_code',
             'code' => 'this_is_an_authorization_code',
         ]);
-        static::assertSame('sk_access_token', $resp->access_token);
+        static::assertSame('sk_access_token', $resp['access_token']);
     }
 
     public function testDeauthorize()
@@ -97,6 +97,6 @@ public function testDeauthorize()
         $resp = OAuth::deauthorize([
             'stripe_user_id' => 'acct_test_deauth',
         ]);
-        static::assertSame('acct_test_deauth', $resp->stripe_user_id);
+        static::assertSame('acct_test_deauth', $resp['stripe_user_id']);
     }
 }
diff --git a/tests/Stripe/Service/OAuthServiceTest.php b/tests/Stripe/Service/OAuthServiceTest.php
index d20e471e5..951ea8176 100644
--- a/tests/Stripe/Service/OAuthServiceTest.php
+++ b/tests/Stripe/Service/OAuthServiceTest.php
@@ -109,7 +109,7 @@ public function testToken()
             'grant_type' => 'authorization_code',
             'code' => 'this_is_an_authorization_code',
         ]);
-        static::assertSame('sk_access_token', $resp->access_token);
+        static::assertSame('sk_access_token', $resp['access_token']);
     }
 
     public function testDeauthorize()
@@ -135,6 +135,6 @@ public function testDeauthorize()
             'client_id' => 'ca_123',
             'stripe_user_id' => 'acct_test',
         ]);
-        static::assertSame('acct_test', $resp->stripe_user_id);
+        static::assertSame('acct_test', $resp['stripe_user_id']);
     }
 }
diff --git a/tests/Stripe/SourceTest.php b/tests/Stripe/SourceTest.php
index 9f34c9d95..7407e5fee 100644
--- a/tests/Stripe/SourceTest.php
+++ b/tests/Stripe/SourceTest.php
@@ -86,12 +86,15 @@ public function testCanSaveCardExpiryDate()
             $response
         );
 
-        $source->card->exp_month = 12;
-        $source->card->exp_year = 2022;
+        /** @var mixed $card */
+        $card = $source->card;
+
+        $card->exp_month = 12;
+        $card->exp_year = 2022;
         $source->save();
 
-        static::assertSame(12, $source->card->exp_month);
-        static::assertSame(2022, $source->card->exp_year);
+        static::assertSame(12, $source['card']['exp_month']);
+        static::assertSame(2022, $source['card']['exp_year']);
     }
 
     public function testIsDetachableWhenAttached()
diff --git a/tests/Stripe/StripeObjectTest.php b/tests/Stripe/StripeObjectTest.php
index f07c47f1e..c8e0903dd 100644
--- a/tests/Stripe/StripeObjectTest.php
+++ b/tests/Stripe/StripeObjectTest.php
@@ -35,6 +35,7 @@ public function setUpReflectors()
 
     public function testArrayAccessorsSemantics()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         $s['foo'] = 'a';
         static::assertSame($s['foo'], 'a');
@@ -45,6 +46,7 @@ public function testArrayAccessorsSemantics()
 
     public function testNormalAccessorsSemantics()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->foo = 'a';
         static::assertSame($s->foo, 'a');
@@ -55,6 +57,7 @@ public function testNormalAccessorsSemantics()
 
     public function testArrayAccessorsMatchNormalAccessors()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->foo = 'a';
         static::assertSame($s['foo'], 'a');
@@ -65,6 +68,7 @@ public function testArrayAccessorsMatchNormalAccessors()
 
     public function testCount()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         static::assertCount(0, $s);
 
@@ -80,6 +84,7 @@ public function testCount()
 
     public function testKeys()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->foo = 'bar';
         static::assertSame($s->keys(), ['foo']);
@@ -87,6 +92,7 @@ public function testKeys()
 
     public function testValues()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->foo = 'bar';
         static::assertSame($s->values(), ['bar']);
@@ -141,6 +147,7 @@ public function testNonexistentProperty()
         $origErrorLog = \ini_set('error_log', \stream_get_meta_data($capture)['uri']);
 
         try {
+            /** @var mixed $s */
             $s = new StripeObject();
             static::assertNull($s->nonexistent);
 
@@ -156,12 +163,14 @@ public function testNonexistentProperty()
 
     public function testPropertyDoesNotExists()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         static::assertNull($s['nonexistent']);
     }
 
     public function testJsonEncode()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->foo = 'a';
 
@@ -170,6 +179,7 @@ public function testJsonEncode()
 
     public function testToString()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->foo = 'a';
 
@@ -184,6 +194,7 @@ public function testToString()
 
     public function testReplaceNewNestedUpdatable()
     {
+        /** @var mixed $s */
         $s = new StripeObject();
 
         $s->metadata = ['bar'];
@@ -196,6 +207,7 @@ public function testSetPermanentAttribute()
     {
         $this->expectException(\InvalidArgumentException::class);
 
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->id = 'abc_123';
     }
@@ -204,6 +216,7 @@ public function testSetEmptyStringValue()
     {
         $this->expectException(\InvalidArgumentException::class);
 
+        /** @var mixed $s */
         $s = new StripeObject();
         $s->foo = '';
     }
@@ -216,6 +229,7 @@ public function testSerializeParametersOnEmptyObject()
 
     public function testSerializeParametersOnNewObjectWithSubObject()
     {
+        /** @var mixed $obj */
         $obj = new StripeObject();
         $obj->metadata = ['foo' => 'bar'];
         static::assertSame(['metadata' => ['foo' => 'bar']], $obj->serializeParameters());
@@ -230,6 +244,7 @@ public function testSerializeParametersOnBasicObject()
 
     public function testSerializeParametersOnMoreComplexObject()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'foo' => StripeObject::constructFrom([
                 'bar' => null,
@@ -242,6 +257,7 @@ public function testSerializeParametersOnMoreComplexObject()
 
     public function testSerializeParametersOnArray()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'foo' => null,
         ]);
@@ -251,6 +267,7 @@ public function testSerializeParametersOnArray()
 
     public function testSerializeParametersOnArrayThatShortens()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'foo' => ['0-index', '1-index', '2-index'],
         ]);
@@ -260,6 +277,7 @@ public function testSerializeParametersOnArrayThatShortens()
 
     public function testSerializeParametersOnArrayThatLengthens()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'foo' => ['0-index', '1-index', '2-index'],
         ]);
@@ -269,17 +287,21 @@ public function testSerializeParametersOnArrayThatLengthens()
 
     public function testSerializeParametersOnArrayOfHashes()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom(['foo' => null]);
         $obj->foo = [
             StripeObject::constructFrom(['bar' => null]),
         ];
 
-        $obj->foo[0]->bar = 'baz';
+        /** @var mixed $first */
+        $first = $obj->foo[0];
+        $first->bar = 'baz';
         static::assertSame(['foo' => [['bar' => 'baz']]], $obj->serializeParameters());
     }
 
     public function testSerializeParametersDoesNotIncludeUnchangedValues()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'foo' => null,
         ]);
@@ -288,6 +310,7 @@ public function testSerializeParametersDoesNotIncludeUnchangedValues()
 
     public function testSerializeParametersOnUnchangedArray()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'foo' => ['0-index', '1-index', '2-index'],
         ]);
@@ -297,6 +320,7 @@ public function testSerializeParametersOnUnchangedArray()
 
     public function testSerializeParametersWithStripeObject()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([]);
         $obj->metadata = StripeObject::constructFrom(['foo' => 'bar']);
 
@@ -306,6 +330,7 @@ public function testSerializeParametersWithStripeObject()
 
     public function testSerializeParametersOnReplacedStripeObject()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'source' => StripeObject::constructFrom(['bar' => 'foo']),
         ]);
@@ -317,6 +342,7 @@ public function testSerializeParametersOnReplacedStripeObject()
 
     public function testSerializeParametersOnReplacedStripeObjectWhichIsMetadata()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'metadata' => StripeObject::constructFrom(['bar' => 'foo']),
         ]);
@@ -328,6 +354,7 @@ public function testSerializeParametersOnReplacedStripeObjectWhichIsMetadata()
 
     public function testSerializeParametersOnArrayOfStripeObjects()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([]);
         $obj->metadata = [
             StripeObject::constructFrom(['foo' => 'bar']),
@@ -340,6 +367,7 @@ public function testSerializeParametersOnArrayOfStripeObjects()
     public function testSerializeParametersOnSetApiResource()
     {
         $customer = Customer::constructFrom(['id' => 'cus_123']);
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([]);
 
         // the key here is that the property is set explicitly (and therefore
@@ -377,6 +405,7 @@ public function testSerializeParametersRaisesExceotionOnOtherEmbeddedApiResource
         // probably not what the user expected to happen.
         $customer = Customer::constructFrom([]);
 
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([]);
         $obj->customer = $customer;
 
@@ -513,6 +542,7 @@ public function testIsDeleted()
 
     public function testDeserializeEmptyMetadata()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'metadata' => [],
         ]);
@@ -522,11 +552,14 @@ public function testDeserializeEmptyMetadata()
 
     public function testDeserializeMetadataWithKeyNamedMetadata()
     {
+        /** @var mixed $obj */
         $obj = StripeObject::constructFrom([
             'metadata' => ['metadata' => 'value'],
         ]);
 
         static::assertInstanceOf(\Stripe\StripeObject::class, $obj->metadata);
-        static::assertSame('value', $obj->metadata->metadata);
+        /** @var mixed $inner */
+        $inner = $obj->metadata;
+        static::assertSame('value', $inner->metadata);
     }
 }
diff --git a/tests/Stripe/StripeTelemetryTest.php b/tests/Stripe/StripeTelemetryTest.php
index 3a27d2260..a76ab2483 100644
--- a/tests/Stripe/StripeTelemetryTest.php
+++ b/tests/Stripe/StripeTelemetryTest.php
@@ -37,7 +37,7 @@ public function testNoTelemetrySentIfNotEnabled()
         $requestheaders = null;
 
         $stub = $this
-            ->getMockBuilder('HttpClient\\ClientInterface')
+            ->getMockBuilder('\\Stripe\\HttpClient\\ClientInterface')
             ->setMethods(['request'])
             ->getMock()
         ;
@@ -80,7 +80,7 @@ public function testTelemetrySetIfEnabled()
         $requestheaders = null;
 
         $stub = $this
-            ->getMockBuilder('HttpClient\\ClientInterface')
+            ->getMockBuilder('\\Stripe\\HttpClient\\ClientInterface')
             ->setMethods(['request'])
             ->getMock()
         ;
diff --git a/tests/Stripe/SubscriptionTest.php b/tests/Stripe/SubscriptionTest.php
index c8d0cabf7..28dc66b1f 100644
--- a/tests/Stripe/SubscriptionTest.php
+++ b/tests/Stripe/SubscriptionTest.php
@@ -94,6 +94,7 @@ public function testCanDeleteDiscount()
 
     public function testSerializeParametersItems()
     {
+        /** @var \Stripe\Subscription */
         $obj = Util\Util::convertToStripeObject([
             'object' => 'subscription',
             'items' => Util\Util::convertToStripeObject([