diff --git a/dune-project b/dune-project
index c6fa7e3..03179bc 100644
--- a/dune-project
+++ b/dune-project
@@ -16,4 +16,5 @@
    ocaml
    dune
    (tsdl (= 1.0.0))
-   (tgls (= 0.8.6))))
+   (tgls (= 0.8.6))
+   (sexplib (= v0.16.0))))
diff --git a/geometra.opam b/geometra.opam
index a64ae0c..d5d307b 100644
--- a/geometra.opam
+++ b/geometra.opam
@@ -5,6 +5,7 @@ depends: [
   "dune" {>= "3.12"}
   "tsdl" {= "1.0.0"}
   "tgls" {= "0.8.6"}
+  "sexplib" {= "v0.16.0"}
   "odoc" {with-doc}
 ]
 build: [