diff --git a/src/Microsoft.AspNetCore.Http.Abstractions/StatusCodes.cs b/src/Microsoft.AspNetCore.Http.Abstractions/StatusCodes.cs
index 9c0f4999..6c28d380 100644
--- a/src/Microsoft.AspNetCore.Http.Abstractions/StatusCodes.cs
+++ b/src/Microsoft.AspNetCore.Http.Abstractions/StatusCodes.cs
@@ -42,6 +42,7 @@ public static class StatusCodes
         public const int Status417ExpectationFailed = 417;
         public const int Status418ImATeapot = 418;
         public const int Status419AuthenticationTimeout = 419;
+        public const int Status451UnavailableForLegalReasons = 451;
 
         public const int Status500InternalServerError = 500;
         public const int Status501NotImplemented = 501;
@@ -51,4 +52,4 @@ public static class StatusCodes
         public const int Status505HttpVersionNotsupported = 505;
         public const int Status506VariantAlsoNegotiates = 506;
     }
-}
\ No newline at end of file
+}