diff --git a/docs/authentication-custom.md b/docs/authentication-custom.md
index 8d7d6a519..4df56f5ba 100644
--- a/docs/authentication-custom.md
+++ b/docs/authentication-custom.md
@@ -16,7 +16,10 @@ services that do this; perhaps this is a market waiting to be tapped?)
 class MySoftware_Auth_Hotdog implements WpOrg\Requests\Auth {
     protected $password;
 
-    public function __construct($password) {
+    public function __construct(
+        #[\SensitiveParameter]
+        $password
+    ) {
         $this->password = $password;
     }
 
diff --git a/src/Auth/Basic.php b/src/Auth/Basic.php
index 829216f82..7c5787a97 100644
--- a/src/Auth/Basic.php
+++ b/src/Auth/Basic.php
@@ -9,6 +9,7 @@
 
 namespace WpOrg\Requests\Auth;
 
+use SensitiveParameter;
 use WpOrg\Requests\Auth;
 use WpOrg\Requests\Exception\ArgumentCount;
 use WpOrg\Requests\Exception\InvalidArgument;
@@ -48,7 +49,10 @@ class Basic implements Auth {
 	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not an array or null.
 	 * @throws \WpOrg\Requests\Exception\ArgumentCount   On incorrect number of array elements (`authbasicbadargs`).
 	 */
-	public function __construct($args = null) {
+	public function __construct(
+		#[SensitiveParameter]
+		$args = null
+	) {
 		if (is_array($args)) {
 			if (count($args) !== 2) {
 				throw ArgumentCount::create('an array with exactly two elements', count($args), 'authbasicbadargs');
diff --git a/src/Proxy/Http.php b/src/Proxy/Http.php
index 2461e47ce..12c901e67 100644
--- a/src/Proxy/Http.php
+++ b/src/Proxy/Http.php
@@ -65,7 +65,10 @@ final class Http implements Proxy {
 	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not an array, a string or null.
 	 * @throws \WpOrg\Requests\Exception\ArgumentCount On incorrect number of arguments (`proxyhttpbadargs`)
 	 */
-	public function __construct($args = null) {
+	public function __construct(
+		#[SensitiveParameter]
+		$args = null
+	) {
 		if (is_string($args)) {
 			$this->proxy = $args;
 		} elseif (is_array($args)) {