diff --git a/pkgs/development/ocaml-modules/mlbdd/default.nix b/pkgs/development/ocaml-modules/mlbdd/default.nix
index 5adf079d24b6..dd72cb9e8f89 100644
--- a/pkgs/development/ocaml-modules/mlbdd/default.nix
+++ b/pkgs/development/ocaml-modules/mlbdd/default.nix
@@ -26,5 +26,6 @@ buildDunePackage {
     homepage = "https://github.com/arlencox/mlbdd";
     description = "Not-quite-so-simple Binary Decision Diagrams implementation for OCaml";
     maintainers = with lib.maintainers; [ katrinafyi ];
+    license = lib.licenses.mit;
   };
 }