diff --git a/src/Keys/AsymmetricPublicKey.php b/src/Keys/AsymmetricPublicKey.php
index b6fa46dd..3ba57f61 100644
--- a/src/Keys/AsymmetricPublicKey.php
+++ b/src/Keys/AsymmetricPublicKey.php
@@ -48,6 +48,7 @@ public function __construct(
 
     /**
      * @return string
+     * @throws \TypeError
      */
     public function encode(): string
     {
@@ -56,7 +57,10 @@ public function encode(): string
 
     /**
      * @param string $encoded
+     *
      * @return self
+     * @throws \Exception
+     * @throws \TypeError
      */
     public static function fromEncodedString(string $encoded): self
     {
diff --git a/src/Keys/AsymmetricSecretKey.php b/src/Keys/AsymmetricSecretKey.php
index 5064d2f4..670eb6f3 100644
--- a/src/Keys/AsymmetricSecretKey.php
+++ b/src/Keys/AsymmetricSecretKey.php
@@ -82,6 +82,7 @@ public static function generate(ProtocolInterface $protocol = null): self
 
     /**
      * @return string
+     * @throws \TypeError
      */
     public function encode(): string
     {
diff --git a/src/ProtocolCollection.php b/src/ProtocolCollection.php
index cba89b23..d3c63e3c 100644
--- a/src/ProtocolCollection.php
+++ b/src/ProtocolCollection.php
@@ -47,6 +47,7 @@ public function __construct(ProtocolInterface ...$protocols)
 
     /**
      * Does the collection contain the given protocol
+     * @param ProtocolInterface $protocol
      *
      * @return bool
      */
@@ -89,7 +90,7 @@ public static function throwIfUnsupported(ProtocolInterface $protocol)
      */
     public static function protocolFromHeader(string $header): ProtocolInterface {
         if (empty(self::$headerLookup)) {
-            /** @var string $protocolClass */
+            /** @var ProtocolInterface $protocolClass */
             foreach (self::WHITELIST as $protocolClass) {
                 self::$headerLookup[$protocolClass::header()] = new $protocolClass;
             }
@@ -106,6 +107,7 @@ public static function protocolFromHeader(string $header): ProtocolInterface {
      * Get a collection of all supported protocols
      *
      * @return self
+     * @throws InvalidVersionException
      */
     public static function default(): self
     {
@@ -123,6 +125,7 @@ function (string $p): ProtocolInterface {
      * Get a collection containing protocol version 1.
      *
      * @return self
+     * @throws InvalidVersionException
      */
     public static function v1(): self
     {
@@ -133,6 +136,7 @@ public static function v1(): self
      * Get a collection containing protocol version 2.
      *
      * @return self
+     * @throws InvalidVersionException
      */
     public static function v2(): self
     {
diff --git a/src/Purpose.php b/src/Purpose.php
index fb35dcd8..fa4bc819 100644
--- a/src/Purpose.php
+++ b/src/Purpose.php
@@ -80,6 +80,7 @@ public function __construct(string $rawString)
      * Create a local purpose.
      *
      * @return self
+     * @throws InvalidPurposeException
      */
     public static function local(): self
     {
@@ -90,6 +91,7 @@ public static function local(): self
      * Create a public purpose.
      *
      * @return self
+     * @throws InvalidPurposeException
      */
     public static function public(): self
     {
@@ -100,7 +102,9 @@ public static function public(): self
      * Given a SendingKey, retrieve the corresponding Purpose.
      *
      * @param SendingKey $key
+     *
      * @return self
+     * @throws InvalidPurposeException
      */
     public static function fromSendingKey(SendingKey $key): self
     {
@@ -117,7 +121,9 @@ public static function fromSendingKey(SendingKey $key): self
      * Given a ReceivingKey, retrieve the corresponding Purpose.
      *
      * @param ReceivingKey $key
+     *
      * @return self
+     * @throws InvalidPurposeException
      */
     public static function fromReceivingKey(ReceivingKey $key): self
     {
@@ -133,7 +139,7 @@ public static function fromReceivingKey(ReceivingKey $key): self
     /**
      * Compare the instance with $purpose in constant time.
      *
-     * @param self $Purpose
+     * @param self $purpose
      * @return bool
      */
     public function equals(self $purpose): bool