diff --git a/src/CallbackStream.php b/src/CallbackStream.php
index f908fd00..1dcb7ae9 100644
--- a/src/CallbackStream.php
+++ b/src/CallbackStream.php
@@ -159,6 +159,7 @@ public function getContents() : string
 
     /**
      * {@inheritdoc}
+     * @return mixed
      */
     public function getMetadata($key = null)
     {
diff --git a/src/RelativeStream.php b/src/RelativeStream.php
index 993a266d..173f62b8 100644
--- a/src/RelativeStream.php
+++ b/src/RelativeStream.php
@@ -169,6 +169,7 @@ public function getContents() : string
 
     /**
      * {@inheritdoc}
+     * @return mixed
      */
     public function getMetadata($key = null)
     {
diff --git a/src/ServerRequest.php b/src/ServerRequest.php
index 313fc055..f5afdbbb 100644
--- a/src/ServerRequest.php
+++ b/src/ServerRequest.php
@@ -165,6 +165,7 @@ public function withQueryParams(array $query) : ServerRequest
 
     /**
      * {@inheritdoc}
+     * @return array|object|null
      */
     public function getParsedBody()
     {
@@ -199,6 +200,7 @@ public function getAttributes() : array
 
     /**
      * {@inheritdoc}
+     * @return mixed
      */
     public function getAttribute($attribute, $default = null)
     {
diff --git a/src/Stream.php b/src/Stream.php
index 063e96c7..74bb7eaf 100644
--- a/src/Stream.php
+++ b/src/Stream.php
@@ -301,6 +301,7 @@ public function getContents() : string
 
     /**
      * {@inheritdoc}
+     * @return mixed
      */
     public function getMetadata($key = null)
     {