diff --git a/src/Key/PrivateKey.php b/src/Key/PrivateKey.php
index f3ea4ca4..ff4ab1b5 100644
--- a/src/Key/PrivateKey.php
+++ b/src/Key/PrivateKey.php
@@ -405,7 +405,7 @@ public function addUsers(array $userIDs): self
     {
         if (empty($userIDs)) {
             throw new \InvalidArgumentException(
-                'UserIDs are required.',
+                'User IDs are required.',
             );
         }
 
diff --git a/src/Packet/SecretKey.php b/src/Packet/SecretKey.php
index e4305319..8f15d013 100644
--- a/src/Packet/SecretKey.php
+++ b/src/Packet/SecretKey.php
@@ -487,7 +487,7 @@ private static function readKeyMaterial(
                 $bytes, $publicKey->getKeyMaterial()
             ),
             default => throw new \UnexpectedValueException(
-                "Unsupported PGP public key algorithm encountered",
+                'Unsupported PGP public key algorithm encountered',
             ),
         };
         if (!$keyMaterial->isValid()) {