diff --git a/src/Call.php b/src/Call.php
index 698c17a26..d5e8d5046 100644
--- a/src/Call.php
+++ b/src/Call.php
@@ -53,14 +53,14 @@ class Call
     /**
      * @param string $method
      * @param string $decodeType
-     * @param Message $message
+     * @param mixed|Message $message
      * @param array $descriptor
      * @param int $callType
      */
     public function __construct(
         $method,
         $decodeType,
-        Message $message = null,
+        $message = null,
         $descriptor = [],
         $callType = Call::UNARY_CALL
     ) {
@@ -96,7 +96,7 @@ public function getDecodeType()
     }
 
     /**
-     * @return Message
+     * @return mixed|Message
      */
     public function getMessage()
     {
@@ -112,10 +112,10 @@ public function getDescriptor()
     }
 
     /**
-     * @param Message $message
+     * @param mixed|Message $message
      * @return Call
      */
-    public function withMessage(Message $message)
+    public function withMessage($message)
     {
         return new static(
             $this->method,
diff --git a/src/Page.php b/src/Page.php
index 7093ce099..ffac92b58 100644
--- a/src/Page.php
+++ b/src/Page.php
@@ -196,7 +196,7 @@ public function iteratePages()
     /**
      * Gets the request object used to generate the Page.
      *
-     * @return \Google\Protobuf\Internal\Message
+     * @return mixed|Message
      */
     public function getRequestObject()
     {
@@ -206,7 +206,7 @@ public function getRequestObject()
     /**
      * Gets the API response object.
      *
-     * @return \Google\Protobuf\Internal\Message
+     * @return mixed|Message
      */
     public function getResponseObject()
     {
diff --git a/src/RequestBuilder.php b/src/RequestBuilder.php
index 7b096c833..ff563557d 100644
--- a/src/RequestBuilder.php
+++ b/src/RequestBuilder.php
@@ -42,6 +42,8 @@
 
 /**
  * Builds a PSR-7 request from a set of request information.
+ *
+ * @internal
  */
 class RequestBuilder
 {
diff --git a/src/UriTrait.php b/src/UriTrait.php
index 3ba9b48b6..bf9094ee7 100644
--- a/src/UriTrait.php
+++ b/src/UriTrait.php
@@ -37,6 +37,8 @@
 
 /**
  * Provides a light wrapper around often used URI related functions.
+ *
+ * @internal
  */
 trait UriTrait
 {