diff --git a/dune-project b/dune-project
index b7885a2..b2d0547 100644
--- a/dune-project
+++ b/dune-project
@@ -7,6 +7,7 @@
 (generate_opam_files)
 
 ; Default attributes of opam packages
+(license "ISC")
 (source (github semgrep/testo))
 (homepage "https://github.com/semgrep/testo")
 (maintainers "Martin Jambon" "OCaml community")