diff --git a/packages/seq/seq.0.2.2/opam b/packages/seq/seq.0.2.2/opam
index 8d9fc2e8236b..79bdcc1d0d0c 100644
--- a/packages/seq/seq.0.2.2/opam
+++ b/packages/seq/seq.0.2.2/opam
@@ -8,7 +8,8 @@ build: [
 ]
 depends: [
   "dune" {>= "1.1.0"}
-  "ocaml"
+  # See https://github.com/c-cube/seq/issues/12
+  "ocaml" {< "4.07.0"}
 ]
 tags: [ "iterator" "seq" "pure" "list" "compatibility" "cascade" ]
 homepage: "https://github.com/c-cube/seq/"