diff --git a/lib/ApiOperations/NestedResource.php b/lib/ApiOperations/NestedResource.php
index 180cacd2c..26af8dc30 100644
--- a/lib/ApiOperations/NestedResource.php
+++ b/lib/ApiOperations/NestedResource.php
@@ -10,7 +10,7 @@
 trait NestedResource
 {
     /**
-     * @param string $method
+     * @param 'delete'|'get'|'post' $method
      * @param string $url
      * @param null|array $params
      * @param null|array|string $options
diff --git a/lib/ApiOperations/Request.php b/lib/ApiOperations/Request.php
index a60ca796a..12df3f2b7 100644
--- a/lib/ApiOperations/Request.php
+++ b/lib/ApiOperations/Request.php
@@ -27,7 +27,7 @@ protected static function _validateParams($params = null)
     }
 
     /**
-     * @param string $method HTTP method ('get', 'post', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method ('get', 'post', etc.)
      * @param string $url URL for the request
      * @param array $params list of parameters for the request
      * @param null|array|string $options
@@ -46,7 +46,7 @@ protected function _request($method, $url, $params = [], $options = null)
     }
 
     /**
-     * @param string $method HTTP method ('get', 'post', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method ('get', 'post', etc.)
      * @param string $url URL for the request
      * @param callable $readBodyChunk function that will receive chunks of data from a successful request body
      * @param array $params list of parameters for the request
@@ -61,7 +61,7 @@ protected function _requestStream($method, $url, $readBodyChunk, $params = [], $
     }
 
     /**
-     * @param string $method HTTP method ('get', 'post', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method ('get', 'post', etc.)
      * @param string $url URL for the request
      * @param array $params list of parameters for the request
      * @param null|array|string $options
@@ -82,7 +82,7 @@ protected static function _staticRequest($method, $url, $params, $options)
     }
 
     /**
-     * @param string $method HTTP method ('get', 'post', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method ('get', 'post', etc.)
      * @param string $url URL for the request
      * @param callable $readBodyChunk function that will receive chunks of data from a successful request body
      * @param array $params list of parameters for the request
diff --git a/lib/ApiRequestor.php b/lib/ApiRequestor.php
index 6a9a9282a..e8f653438 100644
--- a/lib/ApiRequestor.php
+++ b/lib/ApiRequestor.php
@@ -106,7 +106,7 @@ private static function _encodeObjects($d)
     }
 
     /**
-     * @param string     $method
+     * @param 'delete'|'get'|'post' $method
      * @param string     $url
      * @param null|array $params
      * @param null|array $headers
@@ -128,7 +128,7 @@ public function request($method, $url, $params = null, $headers = null)
     }
 
     /**
-     * @param string     $method
+     * @param 'delete'|'get'|'post' $method
      * @param string     $url
      * @param callable $readBodyChunkCallable
      * @param null|array $params
@@ -432,7 +432,7 @@ function ($key) use ($params) {
     }
 
     /**
-     * @param string $method
+     * @param 'delete'|'get'|'post' $method
      * @param string $url
      * @param array $params
      * @param array $headers
@@ -469,7 +469,7 @@ private function _requestRaw($method, $url, $params, $headers)
     }
 
     /**
-     * @param string $method
+     * @param 'delete'|'get'|'post' $method
      * @param string $url
      * @param array $params
      * @param array $headers
diff --git a/lib/BaseStripeClient.php b/lib/BaseStripeClient.php
index b0b2e7e57..a2c1d30d8 100644
--- a/lib/BaseStripeClient.php
+++ b/lib/BaseStripeClient.php
@@ -119,7 +119,7 @@ public function getFilesBase()
     /**
      * Sends a request to Stripe's API.
      *
-     * @param string $method the HTTP method
+     * @param 'delete'|'get'|'post' $method the HTTP method
      * @param string $path the path of the request
      * @param array $params the parameters of the request
      * @param array|\Stripe\Util\RequestOptions $opts the special modifiers of the request
@@ -143,7 +143,7 @@ public function request($method, $path, $params, $opts)
      * Sends a request to Stripe's API, passing chunks of the streamed response
      * into a user-provided $readBodyChunkCallable callback.
      *
-     * @param string $method the HTTP method
+     * @param 'delete'|'get'|'post' $method the HTTP method
      * @param string $path the path of the request
      * @param callable $readBodyChunkCallable a function that will be called
      * @param array $params the parameters of the request
@@ -161,7 +161,7 @@ public function requestStream($method, $path, $readBodyChunkCallable, $params, $
     /**
      * Sends a request to Stripe's API.
      *
-     * @param string $method the HTTP method
+     * @param 'delete'|'get'|'post' $method the HTTP method
      * @param string $path the path of the request
      * @param array $params the parameters of the request
      * @param array|\Stripe\Util\RequestOptions $opts the special modifiers of the request
@@ -185,7 +185,7 @@ public function requestCollection($method, $path, $params, $opts)
     /**
      * Sends a request to Stripe's API.
      *
-     * @param string $method the HTTP method
+     * @param 'delete'|'get'|'post' $method the HTTP method
      * @param string $path the path of the request
      * @param array $params the parameters of the request
      * @param array|\Stripe\Util\RequestOptions $opts the special modifiers of the request
diff --git a/lib/HttpClient/ClientInterface.php b/lib/HttpClient/ClientInterface.php
index 3c7861e59..6d17eb8ae 100644
--- a/lib/HttpClient/ClientInterface.php
+++ b/lib/HttpClient/ClientInterface.php
@@ -5,7 +5,7 @@
 interface ClientInterface
 {
     /**
-     * @param string $method The HTTP method being used
+     * @param 'delete'|'get'|'post' $method The HTTP method being used
      * @param string $absUrl The URL being requested, including domain and protocol
      * @param array $headers Headers to be used in the request (full strings, not KV pairs)
      * @param array $params KV pairs for parameters. Can be nested for arrays and hashes
diff --git a/lib/HttpClient/StreamingClientInterface.php b/lib/HttpClient/StreamingClientInterface.php
index 482f9a119..7612c94a6 100644
--- a/lib/HttpClient/StreamingClientInterface.php
+++ b/lib/HttpClient/StreamingClientInterface.php
@@ -5,7 +5,7 @@
 interface StreamingClientInterface
 {
     /**
-     * @param string $method The HTTP method being used
+     * @param 'delete'|'get'|'post' $method The HTTP method being used
      * @param string $absUrl The URL being requested, including domain and protocol
      * @param array $headers Headers to be used in the request (full strings, not KV pairs)
      * @param array $params KV pairs for parameters. Can be nested for arrays and hashes
diff --git a/lib/Service/OAuthService.php b/lib/Service/OAuthService.php
index b745ad987..3870cccd4 100644
--- a/lib/Service/OAuthService.php
+++ b/lib/Service/OAuthService.php
@@ -7,7 +7,7 @@ class OAuthService extends \Stripe\Service\AbstractService
     /**
      * Sends a request to Stripe's Connect API.
      *
-     * @param string $method the HTTP method
+     * @param 'delete'|'get'|'post' $method the HTTP method
      * @param string $path the path of the request
      * @param array $params the parameters of the request
      * @param array|\Stripe\Util\RequestOptions $opts the special modifiers of the request
diff --git a/lib/StripeClientInterface.php b/lib/StripeClientInterface.php
index d5a8806ff..a18308d72 100644
--- a/lib/StripeClientInterface.php
+++ b/lib/StripeClientInterface.php
@@ -10,7 +10,7 @@ interface StripeClientInterface extends BaseStripeClientInterface
     /**
      * Sends a request to Stripe's API.
      *
-     * @param string $method the HTTP method
+     * @param 'delete'|'get'|'post' $method the HTTP method
      * @param string $path the path of the request
      * @param array $params the parameters of the request
      * @param array|\Stripe\Util\RequestOptions $opts the special modifiers of the request
diff --git a/tests/TestHelper.php b/tests/TestHelper.php
index 350608f2d..95e4ec64b 100644
--- a/tests/TestHelper.php
+++ b/tests/TestHelper.php
@@ -71,7 +71,7 @@ protected function tearDownConfig()
      * Sets up a request expectation with the provided parameters. The request
      * will actually go through and be emitted.
      *
-     * @param string $method HTTP method (e.g. 'post', 'get', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method (e.g. 'post', 'get', etc.)
      * @param string $path relative path (e.g. '/v1/charges')
      * @param null|array $params array of parameters. If null, parameters will
      *   not be checked.
@@ -106,7 +106,7 @@ function ($method, $absUrl, $headers, $params, $hasFile) {
      * Sets up a request expectation with the provided parameters. The request
      * will actually go through and be emitted.
      *
-     * @param string $method HTTP method (e.g. 'post', 'get', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method (e.g. 'post', 'get', etc.)
      * @param string $path relative path (e.g. '/v1/charges')
      * @param null|array $params array of parameters. If null, parameters will
      *   not be checked.
@@ -142,7 +142,7 @@ function ($method, $absUrl, $readBodyChunkCallable, $headers, $params, $hasFile)
      * will not actually be emitted, instead the provided response parameters
      * will be returned.
      *
-     * @param string $method HTTP method (e.g. 'post', 'get', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method (e.g. 'post', 'get', etc.)
      * @param string $path relative path (e.g. '/v1/charges')
      * @param null|array $params array of parameters. If null, parameters will
      *   not be checked.
@@ -175,7 +175,7 @@ protected function stubRequest(
      * prepare the client mocker to expect an invocation of the `request` method
      * with the provided arguments.
      *
-     * @param string $method HTTP method (e.g. 'post', 'get', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method (e.g. 'post', 'get', etc.)
      * @param string $path relative path (e.g. '/v1/charges')
      * @param null|array $params array of parameters. If null, parameters will
      *   not be checked.
@@ -231,7 +231,7 @@ private function prepareRequestMock(
      * prepare the client mocker to expect an invocation of the `request` method
      * with the provided arguments.
      *
-     * @param string $method HTTP method (e.g. 'post', 'get', etc.)
+     * @param 'delete'|'get'|'post' $method HTTP method (e.g. 'post', 'get', etc.)
      * @param string $path relative path (e.g. '/v1/charges')
      * @param null|array $params array of parameters. If null, parameters will
      *   not be checked.