diff --git a/src/HeaderSecurity.php b/src/HeaderSecurity.php
index 231beac0..8f3ffd2e 100644
--- a/src/HeaderSecurity.php
+++ b/src/HeaderSecurity.php
@@ -129,7 +129,7 @@ public static function isValid($value)
     public static function assertValid($value)
     {
         if (! self::isValid($value)) {
-            throw new InvalidArgumentException('Invalid header value');
+            throw new InvalidArgumentException("'$value' is not valid header value");
         }
     }
 
@@ -143,7 +143,7 @@ public static function assertValid($value)
     public static function assertValidName($name)
     {
         if (! preg_match('/^[a-zA-Z0-9\'`#$%&*+.^_|~!-]+$/', $name)) {
-            throw new InvalidArgumentException('Invalid header name');
+            throw new InvalidArgumentException("'$name' is not valid header name");
         }
     }
 }