diff --git a/sidekick.opam b/sidekick.opam
index 1910b373..2432ada2 100644
--- a/sidekick.opam
+++ b/sidekick.opam
@@ -12,8 +12,8 @@ build: [
 ]
 depends: [
   "dune" {build}
-  "containers"
-  "iter"
+  "containers" { >= "2.8" & < "3.0" }
+  "iter" { >= "1.0" & < "2.0" }
   "msat" { >= "0.8.2" < "0.9" }
   "ocaml" { >= "4.03" }
   "alcotest" {with-test}