diff --git a/packages/modulectomy.0.0.1~dev/opam b/packages/modulectomy.0.0.1~dev/opam
index 1e87e50..4550d35 100644
--- a/packages/modulectomy.0.0.1~dev/opam
+++ b/packages/modulectomy.0.0.1~dev/opam
@@ -14,6 +14,7 @@ depends: [
   "owee"
   "iter"
   "containers"
+  "containers-data"
   "fpath"
   "tyxml"
   "tyre"