diff --git a/pkgs/tools/X11/xrestop/default.nix b/pkgs/tools/X11/xrestop/default.nix
index 76e502d7598..4f9b7bcb42e 100644
--- a/pkgs/tools/X11/xrestop/default.nix
+++ b/pkgs/tools/X11/xrestop/default.nix
@@ -14,5 +14,6 @@ stdenv.mkDerivation rec {
 
   meta = {
     platforms = stdenv.lib.platforms.unix;
+    license = stdenv.lib.licenses.gpl2;
   };
 }