diff --git a/pkgs/by-name/xh/xhtml1/package.nix b/pkgs/by-name/xh/xhtml1/package.nix
index 4d13bd1624dc..020abcab5419 100644
--- a/pkgs/by-name/xh/xhtml1/package.nix
+++ b/pkgs/by-name/xh/xhtml1/package.nix
@@ -33,5 +33,6 @@ stdenv.mkDerivation {
     homepage = "https://www.w3.org/TR/xhtml1/";
     description = "DTDs for XHTML 1.0, the Extensible HyperText Markup Language";
     platforms = lib.platforms.unix;
+    license = lib.licenses.w3c-19980720;
   };
 }